christopher/rosetta-code · Datasets at Hugging Face

task_url stringlengths 30 116	task_name stringlengths 2 86	task_description stringlengths 0 14.4k	language_url stringlengths 2 53	language_name stringlengths 1 52	code stringlengths 0 61.9k
http://rosettacode.org/wiki/Reverse_words_in_a_string	Reverse words in a string	Task Reverse the order of all tokens in each of a number of strings and display the result; the order of characters within a token should not be modified. Example Hey you, Bub! would be shown reversed as: Bub! you, Hey Tokens are any non-space characters separated by spaces (formally, white-space); the visible punctuation form part of the word within which it is located and should not be modified. You may assume that there are no significant non-visible characters in the input. Multiple or superfluous spaces may be compressed into a single space. Some strings have no tokens, so an empty string (or one just containing spaces) would be the result. Display the strings in order (1st, 2nd, 3rd, ···), and one string per line. (You can consider the ten strings as ten lines, and the tokens as words.) Input data (ten lines within the box) line ╔════════════════════════════════════════╗ 1 ║ ---------- Ice and Fire ------------ ║ 2 ║ ║ ◄─── a blank line here. 3 ║ fire, in end will world the say Some ║ 4 ║ ice. in say Some ║ 5 ║ desire of tasted I've what From ║ 6 ║ fire. favor who those with hold I ║ 7 ║ ║ ◄─── a blank line here. 8 ║ ... elided paragraph last ... ║ 9 ║ ║ ◄─── a blank line here. 10 ║ Frost Robert ----------------------- ║ ╚════════════════════════════════════════╝ Cf. Phrase reversals	#sed	sed	#!/usr/bin/sed -f G :loop s/^[[:space:]]\([^[:space:]][^[:space:]]\)\(.\n\)/\2 \1/ t loop s/^[[:space:]]//
http://rosettacode.org/wiki/Rot-13	Rot-13	Task Implement a rot-13 function (or procedure, class, subroutine, or other "callable" object as appropriate to your programming environment). Optionally wrap this function in a utility program (like tr, which acts like a common UNIX utility, performing a line-by-line rot-13 encoding of every line of input contained in each file listed on its command line, or (if no filenames are passed thereon) acting as a filter on its "standard input." (A number of UNIX scripting languages and utilities, such as awk and sed either default to processing files in this way or have command line switches or modules to easily implement these wrapper semantics, e.g., Perl and Python). The rot-13 encoding is commonly known from the early days of Usenet "Netnews" as a way of obfuscating text to prevent casual reading of spoiler or potentially offensive material. Many news reader and mail user agent programs have built-in rot-13 encoder/decoders or have the ability to feed a message through any external utility script for performing this (or other) actions. The definition of the rot-13 function is to simply replace every letter of the ASCII alphabet with the letter which is "rotated" 13 characters "around" the 26 letter alphabet from its normal cardinal position (wrapping around from z to a as necessary). Thus the letters abc become nop and so on. Technically rot-13 is a "mono-alphabetic substitution cipher" with a trivial "key". A proper implementation should work on upper and lower case letters, preserve case, and pass all non-alphabetic characters in the input stream through without alteration. Related tasks Caesar cipher Substitution Cipher Vigenère Cipher/Cryptanalysis Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet	#VBScript	VBScript	option explicit function rot13(a) dim b,n1,n,i b="" for i=1 to len(a) n=asc(mid(a,i,1)) if n>=65 and n<= 91 then n1=(((n-65)+13)mod 26)+65 elseif n>=97 and n<= 123 then n1=(((n-97)+13)mod 26)+97 else n1=n end if b=b & chr(n1) next rot13=b end function const a="The quick brown fox jumps over the lazy dog." dim b,c wscript.echo a b=rot13(a) wscript.echo b c=rot13(b) wscript.echo c
http://rosettacode.org/wiki/Roman_numerals/Encode	Roman numerals/Encode	Task Create a function taking a positive integer as its parameter and returning a string containing the Roman numeral representation of that integer. Modern Roman numerals are written by expressing each digit separately, starting with the left most digit and skipping any digit with a value of zero. In Roman numerals: 1990 is rendered: 1000=M, 900=CM, 90=XC; resulting in MCMXC 2008 is written as 2000=MM, 8=VIII; or MMVIII 1666 uses each Roman symbol in descending order: MDCLXVI	#Ursala	Ursala	#import nat roman = -+ 'IIII'%='IV'+ 'VIIII'%='IX'+ 'XXXX'%='XL'+ 'LXXXX'%='XC'+ 'CCCC'%='CD'+ 'DCCCC'%='CM', ~&plrDlSPSL/'MDCLXVI'+ iota*+ +^\|(^\|C/~&,\/division)@rlX=>~&iNC <1000,500,100,50,10,5>+-
http://rosettacode.org/wiki/Repeat_a_string	Repeat a string	Take a string and repeat it some number of times. Example: repeat("ha", 5) => "hahahahaha" If there is a simpler/more efficient way to repeat a single “character” (i.e. creating a string filled with a certain character), you might want to show that as well (i.e. repeat-char("", 5) => "****"). Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet	#LFE	LFE	(string:copies '"ha" 5)
http://rosettacode.org/wiki/Repeat_a_string	Repeat a string	Take a string and repeat it some number of times. Example: repeat("ha", 5) => "hahahahaha" If there is a simpler/more efficient way to repeat a single “character” (i.e. creating a string filled with a certain character), you might want to show that as well (i.e. repeat-char("", 5) => "****"). Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet	#Liberty_BASIC	Liberty BASIC	a$ ="ha " print StringRepeat$( a$, 5) end function StringRepeat$( in$, n) o$ ="" for i =1 to n o$ =o$ +in$ next i StringRepeat$ =o$ end function
http://rosettacode.org/wiki/Return_multiple_values	Return multiple values	Task Show how to return more than one value from a function.	#Ursa	Ursa	def getstrs (int n) decl string<> input while (> n 0) out ": " console append (in string console) input dec n end while return input end getstrs decl int amount out "how many strings do you want to enter? " console set amount (in int console) decl string<> ret set ret (getstrs amount) out endl ret endl console
http://rosettacode.org/wiki/Return_multiple_values	Return multiple values	Task Show how to return more than one value from a function.	#VBA	VBA	Type Contact Name As String firstname As String Age As Byte End Type Function SetContact(N As String, Fn As String, A As Byte) As Contact SetContact.Name = N SetContact.firstname = Fn SetContact.Age = A End Function 'For use : Sub Test_SetContact() Dim Cont As Contact Cont = SetContact("SMITH", "John", 23) Debug.Print Cont.Name & " " & Cont.firstname & ", " & Cont.Age & " years old." End Sub
http://rosettacode.org/wiki/Remove_duplicate_elements	Remove duplicate elements	Sorting Algorithm This is a sorting algorithm. It may be applied to a set of data in order to sort it. For comparing various sorts, see compare sorts. For other sorting algorithms, see sorting algorithms, or: O(n logn) sorts Heap sort \| Merge sort \| Patience sort \| Quick sort O(n log2n) sorts Shell Sort O(n2) sorts Bubble sort \| Cocktail sort \| Cocktail sort with shifting bounds \| Comb sort \| Cycle sort \| Gnome sort \| Insertion sort \| Selection sort \| Strand sort other sorts Bead sort \| Bogo sort \| Common sorted list \| Composite structures sort \| Custom comparator sort \| Counting sort \| Disjoint sublist sort \| External sort \| Jort sort \| Lexicographical sort \| Natural sorting \| Order by pair comparisons \| Order disjoint list items \| Order two numerical lists \| Object identifier (OID) sort \| Pancake sort \| Quickselect \| Permutation sort \| Radix sort \| Ranking methods \| Remove duplicate elements \| Sleep sort \| Stooge sort \| [Sort letters of a string] \| Three variable sort \| Topological sort \| Tree sort Given an Array, derive a sequence of elements in which all duplicates are removed. There are basically three approaches seen here: Put the elements into a hash table which does not allow duplicates. The complexity is O(n) on average, and O(n2) worst case. This approach requires a hash function for your type (which is compatible with equality), either built-in to your language, or provided by the user. Sort the elements and remove consecutive duplicate elements. The complexity of the best sorting algorithms is O(n log n). This approach requires that your type be "comparable", i.e., have an ordering. Putting the elements into a self-balancing binary search tree is a special case of sorting. Go through the list, and for each element, check the rest of the list to see if it appears again, and discard it if it does. The complexity is O(n2). The up-shot is that this always works on any type (provided that you can test for equality).	#Inform_7	Inform 7	To decide which list of Ks is (L - list of values of kind K) without duplicates: let result be a list of Ks; repeat with X running through L: add X to result, if absent; decide on result.
http://rosettacode.org/wiki/Reduced_row_echelon_form	Reduced row echelon form	Reduced row echelon form You are encouraged to solve this task according to the task description, using any language you may know. Task Show how to compute the reduced row echelon form (a.k.a. row canonical form) of a matrix. The matrix can be stored in any datatype that is convenient (for most languages, this will probably be a two-dimensional array). Built-in functions or this pseudocode (from Wikipedia) may be used: function ToReducedRowEchelonForm(Matrix M) is lead := 0 rowCount := the number of rows in M columnCount := the number of columns in M for 0 ≤ r < rowCount do if columnCount ≤ lead then stop end if i = r while M[i, lead] = 0 do i = i + 1 if rowCount = i then i = r lead = lead + 1 if columnCount = lead then stop end if end if end while Swap rows i and r If M[r, lead] is not 0 divide row r by M[r, lead] for 0 ≤ i < rowCount do if i ≠ r do Subtract M[i, lead] multiplied by row r from row i end if end for lead = lead + 1 end for end function For testing purposes, the RREF of this matrix: 1 2 -1 -4 2 3 -1 -11 -2 0 -3 22 is: 1 0 0 -8 0 1 0 1 0 0 1 -2	#Perl	Perl	sub rref {our @m; local m = shift; @m or return; my ($lead, $rows, $cols) = (0, scalar(@m), scalar(@{$m[0]})); foreach my $r (0 .. $rows - 1) {$lead < $cols or return; my $i = $r; until ($m[$i][$lead]) {++$i == $rows or next; $i = $r; ++$lead == $cols and return;} @m[$i, $r] = @m[$r, $i]; my $lv = $m[$r][$lead]; $_ /= $lv foreach @{ $m[$r] }; my @mr = @{ $m[$r] }; foreach my $i (0 .. $rows - 1) {$i == $r and next; ($lv, my $n) = ($m[$i][$lead], -1); $_ -= $lv $mr[++$n] foreach @{ $m[$i] };} ++$lead;}} sub display { join("\n" => map join(" " => map(sprintf("%4d", $_), @$_)), @{+shift})."\n" } @m = ( [ 1, 2, -1, -4 ], [ 2, 3, -1, -11 ], [ -2, 0, -3, 22 ] ); rref(\@m); print display(\@m);
http://rosettacode.org/wiki/Real_constants_and_functions	Real constants and functions	Task Show how to use the following math constants and functions in your language (if not available, note it): e (base of the natural logarithm) π {\displaystyle \pi } square root logarithm (any base allowed) exponential (ex ) absolute value (a.k.a. "magnitude") floor (largest integer less than or equal to this number--not the same as truncate or int) ceiling (smallest integer not less than this number--not the same as round up) power (xy ) Related task Trigonometric Functions	#Logo	Logo	make "e exp 1 make "pi 2*(RADARCTAN 0 1) sqrt :x ln :x exp :x ; there is no standard abs, floor, or ceiling; only INT and ROUND. power :x :y
http://rosettacode.org/wiki/Real_constants_and_functions	Real constants and functions	Task Show how to use the following math constants and functions in your language (if not available, note it): e (base of the natural logarithm) π {\displaystyle \pi } square root logarithm (any base allowed) exponential (ex ) absolute value (a.k.a. "magnitude") floor (largest integer less than or equal to this number--not the same as truncate or int) ceiling (smallest integer not less than this number--not the same as round up) power (xy ) Related task Trigonometric Functions	#Logtalk	Logtalk	:- object(constants_and_functions). :- public(show/0). show :- write('e = '), E is e, write(E), nl, write('pi = '), PI is pi, write(PI), nl, write('sqrt(2) = '), SQRT is sqrt(2), write(SQRT), nl, % only base e logorithm is avaialable as a standard built-in function write('log(2) = '), LOG is log(2), write(LOG), nl, write('exp(2) = '), EXP is exp(2), write(EXP), nl, write('abs(-1) = '), ABS is abs(-1), write(ABS), nl, write('floor(-3.4) = '), FLOOR is floor(-3.4), write(FLOOR), nl, write('ceiling(-3.4) = '), CEILING is ceiling(-3.4), write(CEILING), nl, write('2 -3.4 = '), POWER is 2 -3.4, write(POWER), nl. :- end_object.
http://rosettacode.org/wiki/Remove_lines_from_a_file	Remove lines from a file	Task Remove a specific line or a number of lines from a file. This should be implemented as a routine that takes three parameters (filename, starting line, and the number of lines to be removed). For the purpose of this task, line numbers and the number of lines start at one, so to remove the first two lines from the file foobar.txt, the parameters should be: foobar.txt, 1, 2 Empty lines are considered and should still be counted, and if the specified line is empty, it should still be removed. An appropriate message should appear if an attempt is made to remove lines beyond the end of the file.	#Tcl	Tcl	proc removeLines {fileName startLine count} { # Work out range to remove set from [expr {$startLine - 1}] set to [expr {$startLine + $count - 2}] # Read the lines set f [open $fileName] set lines [split [read $f] "\n"] close $f # Write the lines back out, without removed range set f [open $fileName w] puts -nonewline $f [join [lreplace $lines $from $to] "\n"] close $f }
http://rosettacode.org/wiki/Read_entire_file	Read entire file	Task Load the entire contents of some text file as a single string variable. If applicable, discuss: encoding selection, the possibility of memory-mapping. Of course, in practice one should avoid reading an entire file at once if the file is large and the task can be accomplished incrementally instead (in which case check File IO); this is for those cases where having the entire file is actually what is wanted.	#Neko	Neko	/** Read entire file Tectonics: nekoc read-entire-file.neko neko read-entire-file */ var file_contents = $loader.loadprim("std@file_contents", 1); try { var entire_file = file_contents("read-entire-file.neko"); $print("Read: ", $ssize(entire_file), " bytes\n"); } catch e { $print("Exception: ", e, "\n"); }
http://rosettacode.org/wiki/Read_entire_file	Read entire file	Task Load the entire contents of some text file as a single string variable. If applicable, discuss: encoding selection, the possibility of memory-mapping. Of course, in practice one should avoid reading an entire file at once if the file is large and the task can be accomplished incrementally instead (in which case check File IO); this is for those cases where having the entire file is actually what is wanted.	#NetRexx	NetRexx	/* NetRexx */ options replace format comments java crossref symbols nobinary parse arg inFileName . if inFileName = '' \| inFileName = '.' then inFileName = './data/dwarfs.json' fileContents = slurp(inFileName) say fileContents return -- Slurp a file and return contents as a Rexx string method slurp(inFileName) public static returns Rexx slurped = Rexx null slurpStr = StringBuilder() ioBuffer = byte[1024] inBytes = int 0 do inFile = File(inFileName) inFileIS = BufferedInputStream(FileInputStream(inFile)) loop label ioLoop until inBytes = -1 slurpStr.append(String(ioBuffer, 0, inBytes)) inBytes = inFileIS.read(ioBuffer) end ioLoop catch exFNF = FileNotFoundException exFNF.printStackTrace catch exIO = IOException exIO.printStackTrace finally do inFileIS.close() catch ex = IOException ex.printStackTrace end end slurped = Rexx(slurpStr.toString) return slurped
http://rosettacode.org/wiki/Rep-string	Rep-string	Given a series of ones and zeroes in a string, define a repeated string or rep-string as a string which is created by repeating a substring of the first N characters of the string truncated on the right to the length of the input string, and in which the substring appears repeated at least twice in the original. For example, the string 10011001100 is a rep-string as the leftmost four characters of 1001 are repeated three times and truncated on the right to give the original string. Note that the requirement for having the repeat occur two or more times means that the repeating unit is never longer than half the length of the input string. Task Write a function/subroutine/method/... that takes a string and returns an indication of if it is a rep-string and the repeated string. (Either the string that is repeated, or the number of repeated characters would suffice). There may be multiple sub-strings that make a string a rep-string - in that case an indication of all, or the longest, or the shortest would suffice. Use the function to indicate the repeating substring if any, in the following: 1001110011 1110111011 0010010010 1010101010 1111111111 0100101101 0100100 101 11 00 1 Show your output on this page. Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet	#Yabasic	Yabasic	data "1001110011", "1110111011", "0010010010", "1010101010", "1111111111", "0100101101", "0100100", "101", "11", "00", "1", "" sub rep$(c$, n) local r$, i for i = 1 to n r$ = r$ + c$ next return r$ end sub do read p$ : if p$ = "" break b$ = "" : l = len(p$) : m = int(l / 2) for i = m to 1 step -1 t$ = left$(p$, i) s$ = rep$(t$, l / i + 1) if p$ = left$(s$, l) b$ = t$ : break next if b$ = "" then print p$, " is not a repeated string" else print p$, " is composed of ", b$, " repeated" end if loop
http://rosettacode.org/wiki/Rep-string	Rep-string	Given a series of ones and zeroes in a string, define a repeated string or rep-string as a string which is created by repeating a substring of the first N characters of the string truncated on the right to the length of the input string, and in which the substring appears repeated at least twice in the original. For example, the string 10011001100 is a rep-string as the leftmost four characters of 1001 are repeated three times and truncated on the right to give the original string. Note that the requirement for having the repeat occur two or more times means that the repeating unit is never longer than half the length of the input string. Task Write a function/subroutine/method/... that takes a string and returns an indication of if it is a rep-string and the repeated string. (Either the string that is repeated, or the number of repeated characters would suffice). There may be multiple sub-strings that make a string a rep-string - in that case an indication of all, or the longest, or the shortest would suffice. Use the function to indicate the repeating substring if any, in the following: 1001110011 1110111011 0010010010 1010101010 1111111111 0100101101 0100100 101 11 00 1 Show your output on this page. Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet	#zkl	zkl	fcn repString(s){ foreach n in ([s.len()/2+1..1,-1]){ Walker.cycle(s[0,n]).pump(s.len(),String) : if(_==s and n*2<=s.len()) return(n); } return(False) }
http://rosettacode.org/wiki/Regular_expressions	Regular expressions	Task match a string against a regular expression substitute part of a string using a regular expression	#Sidef	Sidef	var str = "I am a string"; if (str =~ /string$/) { print "Ends with 'string'\n"; }
http://rosettacode.org/wiki/Regular_expressions	Regular expressions	Task match a string against a regular expression substitute part of a string using a regular expression	#Slate	Slate	'http://slatelanguage.org/test/page?query' =~ '^(([^:/?#]+)\\:)?(//([^/?#]))?([^?#])(\\?([^#]))?(#(.))?'. " ==> {'http:'. 'http'. '//slatelanguage.org'. 'slatelanguage.org'. '/test/page'. '?query'. 'query'. Nil} "
http://rosettacode.org/wiki/Reverse_a_string	Reverse a string	Task Take a string and reverse it. For example, "asdf" becomes "fdsa". Extra credit Preserve Unicode combining characters. For example, "as⃝df̅" becomes "f̅ds⃝a", not "̅fd⃝sa". Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet	#EGL	EGL	function reverse( str string ) returns( string ) result string; for ( i int from StrLib.characterLen( str ) to 1 decrement by 1 ) result ::= str[i:i]; end return( result ); end
http://rosettacode.org/wiki/Rename_a_file	Rename a file	Task Rename: a file called input.txt into output.txt and a directory called docs into mydocs. This should be done twice: once "here", i.e. in the current working directory and once in the filesystem root. It can be assumed that the user has the rights to do so. (In unix-type systems, only the user root would have sufficient permissions in the filesystem root.)	#Yorick	Yorick	rename, "input.txt", "output.txt"; rename, "/input.txt", "/output.txt"; rename, "docs", "mydocs"; rename, "/docs", "/mydocs";
http://rosettacode.org/wiki/Rename_a_file	Rename a file	Task Rename: a file called input.txt into output.txt and a directory called docs into mydocs. This should be done twice: once "here", i.e. in the current working directory and once in the filesystem root. It can be assumed that the user has the rights to do so. (In unix-type systems, only the user root would have sufficient permissions in the filesystem root.)	#zkl	zkl	ls -ld input.txt docs output.txt mydocs ls: cannot access 'output.txt': No such file or directory ls: cannot access 'mydocs': No such file or directory drwxr-xr-x 2 craigd craigd 4096 Aug 10 16:24 docs -rw-r--r-- 1 craigd craigd 0 Aug 10 16:24 input.txt $ zkl zkl: File.rename("input.txt","output.txt") True zkl: File.rename("docs","mydocs") True zkl: ^D $ ls -ld input.txt docs output.txt mydocs ls: cannot access 'input.txt': No such file or directory ls: cannot access 'docs': No such file or directory drwxr-xr-x 2 craigd craigd 4096 Aug 10 16:24 mydocs -rw-r--r-- 1 craigd craigd 0 Aug 10 16:24 output.txt
http://rosettacode.org/wiki/Reverse_words_in_a_string	Reverse words in a string	Task Reverse the order of all tokens in each of a number of strings and display the result; the order of characters within a token should not be modified. Example Hey you, Bub! would be shown reversed as: Bub! you, Hey Tokens are any non-space characters separated by spaces (formally, white-space); the visible punctuation form part of the word within which it is located and should not be modified. You may assume that there are no significant non-visible characters in the input. Multiple or superfluous spaces may be compressed into a single space. Some strings have no tokens, so an empty string (or one just containing spaces) would be the result. Display the strings in order (1st, 2nd, 3rd, ···), and one string per line. (You can consider the ten strings as ten lines, and the tokens as words.) Input data (ten lines within the box) line ╔════════════════════════════════════════╗ 1 ║ ---------- Ice and Fire ------------ ║ 2 ║ ║ ◄─── a blank line here. 3 ║ fire, in end will world the say Some ║ 4 ║ ice. in say Some ║ 5 ║ desire of tasted I've what From ║ 6 ║ fire. favor who those with hold I ║ 7 ║ ║ ◄─── a blank line here. 8 ║ ... elided paragraph last ... ║ 9 ║ ║ ◄─── a blank line here. 10 ║ Frost Robert ----------------------- ║ ╚════════════════════════════════════════╝ Cf. Phrase reversals	#Seed7	Seed7	$ include "seed7_05.s7i"; const array string: lines is [] ( "---------- Ice and Fire ------------", "", "fire, in end will world the say Some", "ice. in say Some", "desire of tasted I've what From", "fire. favor who those with hold I", "", "... elided paragraph last ...", "", "Frost Robert -----------------------"); const proc: main is func local var string: line is ""; var array string: words is 0 times ""; var integer: index is 0; begin for line range lines do words := split(line, ' '); for index range length(words) downto 1 do write(words[index] <& " "); end for; writeln; end for; end func;
http://rosettacode.org/wiki/Reverse_words_in_a_string	Reverse words in a string	Task Reverse the order of all tokens in each of a number of strings and display the result; the order of characters within a token should not be modified. Example Hey you, Bub! would be shown reversed as: Bub! you, Hey Tokens are any non-space characters separated by spaces (formally, white-space); the visible punctuation form part of the word within which it is located and should not be modified. You may assume that there are no significant non-visible characters in the input. Multiple or superfluous spaces may be compressed into a single space. Some strings have no tokens, so an empty string (or one just containing spaces) would be the result. Display the strings in order (1st, 2nd, 3rd, ···), and one string per line. (You can consider the ten strings as ten lines, and the tokens as words.) Input data (ten lines within the box) line ╔════════════════════════════════════════╗ 1 ║ ---------- Ice and Fire ------------ ║ 2 ║ ║ ◄─── a blank line here. 3 ║ fire, in end will world the say Some ║ 4 ║ ice. in say Some ║ 5 ║ desire of tasted I've what From ║ 6 ║ fire. favor who those with hold I ║ 7 ║ ║ ◄─── a blank line here. 8 ║ ... elided paragraph last ... ║ 9 ║ ║ ◄─── a blank line here. 10 ║ Frost Robert ----------------------- ║ ╚════════════════════════════════════════╝ Cf. Phrase reversals	#SenseTalk	SenseTalk	set poem to {{ ---------- Ice and Fire ------------ fire, in end will world the say Some ice. in say Some desire of tasted I've what From fire. favor who those with hold I ... elided paragraph last ... Frost Robert ----------------------- }} repeat with each line in poem put (each word of it) reversed joined by space end repeat
http://rosettacode.org/wiki/Rot-13	Rot-13	Task Implement a rot-13 function (or procedure, class, subroutine, or other "callable" object as appropriate to your programming environment). Optionally wrap this function in a utility program (like tr, which acts like a common UNIX utility, performing a line-by-line rot-13 encoding of every line of input contained in each file listed on its command line, or (if no filenames are passed thereon) acting as a filter on its "standard input." (A number of UNIX scripting languages and utilities, such as awk and sed either default to processing files in this way or have command line switches or modules to easily implement these wrapper semantics, e.g., Perl and Python). The rot-13 encoding is commonly known from the early days of Usenet "Netnews" as a way of obfuscating text to prevent casual reading of spoiler or potentially offensive material. Many news reader and mail user agent programs have built-in rot-13 encoder/decoders or have the ability to feed a message through any external utility script for performing this (or other) actions. The definition of the rot-13 function is to simply replace every letter of the ASCII alphabet with the letter which is "rotated" 13 characters "around" the 26 letter alphabet from its normal cardinal position (wrapping around from z to a as necessary). Thus the letters abc become nop and so on. Technically rot-13 is a "mono-alphabetic substitution cipher" with a trivial "key". A proper implementation should work on upper and lower case letters, preserve case, and pass all non-alphabetic characters in the input stream through without alteration. Related tasks Caesar cipher Substitution Cipher Vigenère Cipher/Cryptanalysis Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet	#Wart	Wart	def (rot13 s) (as string (map rot13 (as list s))) Alphabet <- "abcdefghijklmnopqrstuvwxyz" def (rot13 c) :case (and string?.c len.c=1) if ("a" <= c <= "z") let idx (pos c Alphabet) Alphabet (idx+13 % 26) ("A" <= c <= "Z") (downcase.c -> rot13 -> upcase) :else c
http://rosettacode.org/wiki/Roman_numerals/Encode	Roman numerals/Encode	Task Create a function taking a positive integer as its parameter and returning a string containing the Roman numeral representation of that integer. Modern Roman numerals are written by expressing each digit separately, starting with the left most digit and skipping any digit with a value of zero. In Roman numerals: 1990 is rendered: 1000=M, 900=CM, 90=XC; resulting in MCMXC 2008 is written as 2000=MM, 8=VIII; or MMVIII 1666 uses each Roman symbol in descending order: MDCLXVI	#Vala	Vala	string to_roman(int n) requires (n > 0 && n < 5000) { const int[] weights = {1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1}; const string[] symbols = {"M","CM","D","CD","C","XC","L", "XL","X","IX","V","IV","I"}; var roman = "", count = 0; foreach (var w in weights) { while (n >= w) { roman += symbols[count]; n -= w; } if (n == 0) break; count++; } return roman; } void main() { print("%s\n", to_roman(455)); print("%s\n", to_roman(3456)); print("%s\n", to_roman(2488)); }
http://rosettacode.org/wiki/Repeat_a_string	Repeat a string	Take a string and repeat it some number of times. Example: repeat("ha", 5) => "hahahahaha" If there is a simpler/more efficient way to repeat a single “character” (i.e. creating a string filled with a certain character), you might want to show that as well (i.e. repeat-char("", 5) => "****"). Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet	#Lingo	Lingo	on rep (str, n) res = "" repeat with i = 1 to n put str after res end repeat return res end
http://rosettacode.org/wiki/Return_multiple_values	Return multiple values	Task Show how to return more than one value from a function.	#Visual_FoxPro	Visual FoxPro	! Return multiple values from a function ! The simplest way is to pass the parameters by reference ! either by SET UDFPARMS TO REFERENCE, or prefix the variables with @. LOCAL a, b a = 5 b = 6 ? "Sum =", AddUp(@a, @b) && Displays 11 ? "a =", a, "b =", b && Displays 4, 5 ? "Sum =", AddUp(@a, @b) && Displays 9 FUNCTION AddUp(n1, n2) LOCAL n n = n1 + n2 n1 = n1 - 1 n2 = n2 - 1 RETURN n ENDFUNC
http://rosettacode.org/wiki/Return_multiple_values	Return multiple values	Task Show how to return more than one value from a function.	#Wren	Wren	var splitName = Fn.new { \|fullName\| fullName.split(" ") } var names = splitName.call("George Bernard Shaw") System.print("First name: %(names[0]), middle name: %(names[1]) and surname: %(names[2]).")
http://rosettacode.org/wiki/Remove_duplicate_elements	Remove duplicate elements	Sorting Algorithm This is a sorting algorithm. It may be applied to a set of data in order to sort it. For comparing various sorts, see compare sorts. For other sorting algorithms, see sorting algorithms, or: O(n logn) sorts Heap sort \| Merge sort \| Patience sort \| Quick sort O(n log2n) sorts Shell Sort O(n2) sorts Bubble sort \| Cocktail sort \| Cocktail sort with shifting bounds \| Comb sort \| Cycle sort \| Gnome sort \| Insertion sort \| Selection sort \| Strand sort other sorts Bead sort \| Bogo sort \| Common sorted list \| Composite structures sort \| Custom comparator sort \| Counting sort \| Disjoint sublist sort \| External sort \| Jort sort \| Lexicographical sort \| Natural sorting \| Order by pair comparisons \| Order disjoint list items \| Order two numerical lists \| Object identifier (OID) sort \| Pancake sort \| Quickselect \| Permutation sort \| Radix sort \| Ranking methods \| Remove duplicate elements \| Sleep sort \| Stooge sort \| [Sort letters of a string] \| Three variable sort \| Topological sort \| Tree sort Given an Array, derive a sequence of elements in which all duplicates are removed. There are basically three approaches seen here: Put the elements into a hash table which does not allow duplicates. The complexity is O(n) on average, and O(n2) worst case. This approach requires a hash function for your type (which is compatible with equality), either built-in to your language, or provided by the user. Sort the elements and remove consecutive duplicate elements. The complexity of the best sorting algorithms is O(n log n). This approach requires that your type be "comparable", i.e., have an ordering. Putting the elements into a self-balancing binary search tree is a special case of sorting. Go through the list, and for each element, check the rest of the list to see if it appears again, and discard it if it does. The complexity is O(n2). The up-shot is that this always works on any type (provided that you can test for equality).	#IS-BASIC	IS-BASIC	100 PROGRAM "RemoveDu.bas" 110 RANDOMIZE 120 NUMERIC ARR(1 TO 20),TOP 130 LET TOP=FILL(ARR) 140 CALL WRITE(ARR,TOP) 150 LET TOP=REMOVE(ARR) 160 CALL WRITE(ARR,TOP) 170 DEF WRITE(REF A,N) 180 FOR I=1 TO N 190 PRINT A(I); 200 NEXT 210 PRINT 220 END DEF 230 DEF FILL(REF A) 240 LET FILL=UBOUND(A):LET A(LBOUND(A))=1 250 FOR I=LBOUND(A)+1 TO UBOUND(A) 260 LET A(I)=A(I-1)+RND(3) 270 NEXT 280 END DEF 290 DEF REMOVE(REF A) 300 LET ST=0 310 FOR I=LBOUND(A)+1 TO UBOUND(A) 320 IF A(I-1)=A(I) THEN LET ST=ST+1 330 IF ST>0 THEN LET A(I-ST)=A(I) 340 NEXT 350 LET REMOVE=UBOUND(A)-ST 360 END DEF
http://rosettacode.org/wiki/Reduced_row_echelon_form	Reduced row echelon form	Reduced row echelon form You are encouraged to solve this task according to the task description, using any language you may know. Task Show how to compute the reduced row echelon form (a.k.a. row canonical form) of a matrix. The matrix can be stored in any datatype that is convenient (for most languages, this will probably be a two-dimensional array). Built-in functions or this pseudocode (from Wikipedia) may be used: function ToReducedRowEchelonForm(Matrix M) is lead := 0 rowCount := the number of rows in M columnCount := the number of columns in M for 0 ≤ r < rowCount do if columnCount ≤ lead then stop end if i = r while M[i, lead] = 0 do i = i + 1 if rowCount = i then i = r lead = lead + 1 if columnCount = lead then stop end if end if end while Swap rows i and r If M[r, lead] is not 0 divide row r by M[r, lead] for 0 ≤ i < rowCount do if i ≠ r do Subtract M[i, lead] multiplied by row r from row i end if end for lead = lead + 1 end for end function For testing purposes, the RREF of this matrix: 1 2 -1 -4 2 3 -1 -11 -2 0 -3 22 is: 1 0 0 -8 0 1 0 1 0 0 1 -2	#Phix	Phix	with javascript_semantics function ToReducedRowEchelonForm(sequence M) integer lead = 1, rowCount = length(M), columnCount = length(M[1]), i for r=1 to rowCount do if lead>=columnCount then exit end if i = r while M[i][lead]=0 do i += 1 if i=rowCount then i = r lead += 1 if lead=columnCount then exit end if end if end while object mr = sq_div(M[i],M[i][lead]) M[i] = M[r] M[r] = mr for j=1 to rowCount do if j!=r then M[j] = sq_sub(M[j],sq_mul(M[j][lead],M[r])) end if end for lead += 1 end for return M end function ? ToReducedRowEchelonForm( { { 1, 2, -1, -4 }, { 2, 3, -1, -11 }, { -2, 0, -3, 22 } })
http://rosettacode.org/wiki/Real_constants_and_functions	Real constants and functions	Task Show how to use the following math constants and functions in your language (if not available, note it): e (base of the natural logarithm) π {\displaystyle \pi } square root logarithm (any base allowed) exponential (ex ) absolute value (a.k.a. "magnitude") floor (largest integer less than or equal to this number--not the same as truncate or int) ceiling (smallest integer not less than this number--not the same as round up) power (xy ) Related task Trigonometric Functions	#Lua	Lua	math.exp(1) math.pi math.sqrt(x) math.log(x) math.log10(x) math.exp(x) math.abs(x) math.floor(x) math.ceil(x) x^y
http://rosettacode.org/wiki/Real_constants_and_functions	Real constants and functions	Task Show how to use the following math constants and functions in your language (if not available, note it): e (base of the natural logarithm) π {\displaystyle \pi } square root logarithm (any base allowed) exponential (ex ) absolute value (a.k.a. "magnitude") floor (largest integer less than or equal to this number--not the same as truncate or int) ceiling (smallest integer not less than this number--not the same as round up) power (xy ) Related task Trigonometric Functions	#M2000_Interpreter	M2000 Interpreter	Module Checkit { Def exp(x)= 2.71828182845905^x Print Ln(exp(1))==1 Print Log(10^5)==5 Print Sgn(-5)=-1 Print Abs(-2.10#)=2.1# Def exptype$(x)=type$(x) Print exptype$(Abs(-2.1#))="Currency" Print exptype$(Abs(-2.1~))="Single" Print exptype$(Abs(-2.1@))="Decimal" Print exptype$(Abs(-2&))="Long" Print exptype$(Abs(-2%))="Integer" Print exptype$(Abs(-2.212e34))="Double" Print exptype$(Sgn(-2.1#))="Integer" \\ Sgn return integer type Print exptype$(Sgn(-2.212e34))="Integer" \\ Log, Len return double Print exptype$(Log(1000))="Double" Print exptype$(exp(1%))="Double" Print exptype$(Ln(1212%))="Double" \\ power return type Double Print exptype$(2&^2&)="Double" Print exptype$(2&*2&)="Double" Print exptype$(2&2&)="Long" Print 22=4, 2^2=4, 2^2^2=16, 22**2=16 \\ floor() and Int() is the same Print Int(-2.7)=-3, Int(2.7)=2 Print Floor(-2.7)=-3, Floor(2.7)=2 Print Ceil(-2.7)=-2, Ceil(2.7)=3 Print round(-2.7, 0)=-3, round(2.7, 0)=3 Print round(-2.2, 0)=-2, round(2.2, 0)=2 Print Sqrt(4)=2 } Checkit
http://rosettacode.org/wiki/Remove_lines_from_a_file	Remove lines from a file	Task Remove a specific line or a number of lines from a file. This should be implemented as a routine that takes three parameters (filename, starting line, and the number of lines to be removed). For the purpose of this task, line numbers and the number of lines start at one, so to remove the first two lines from the file foobar.txt, the parameters should be: foobar.txt, 1, 2 Empty lines are considered and should still be counted, and if the specified line is empty, it should still be removed. An appropriate message should appear if an attempt is made to remove lines beyond the end of the file.	#TUSCRIPT	TUSCRIPT	$$! input=testfile,begnr=3,endnr=4 $$ MODE TUSCRIPT - CREATE inputfile ERROR/STOP CREATE (input,FDF-o,-std-) FILE/ERASE $input LOOP n=1,9 content=CONCAT ("line",n) DATA {content} ENDLOOP ENDFILE - CREATE outputfile output="outputfile" ERROR/STOP CREATE (output,fdf-o,-std-) ACCESS q: READ/RECORDS/utf8 $input L,line ACCESS z: WRITE/RECORDS/utf8 $output L,line PRINT "content: of output-file" LOOP/9999 READ/NEXT/EXIT q IF (begnr<=L&&endnr>=L) CYCLE PRINT line WRITE z ENDLOOP ENDACCESS/PRINT q ENDACCESS/PRINT z
http://rosettacode.org/wiki/Read_entire_file	Read entire file	Task Load the entire contents of some text file as a single string variable. If applicable, discuss: encoding selection, the possibility of memory-mapping. Of course, in practice one should avoid reading an entire file at once if the file is large and the task can be accomplished incrementally instead (in which case check File IO); this is for those cases where having the entire file is actually what is wanted.	#NewLISP	NewLISP	(read-file "filename")
http://rosettacode.org/wiki/Regular_expressions	Regular expressions	Task match a string against a regular expression substitute part of a string using a regular expression	#Smalltalk	Smalltalk	\|re s s1\| re := Regex fromString: '[a-z]+ing'. s := 'this is a matching string'. s1 := 'this does not match'. (s =~ re) ifMatched: [ :b \| b match displayNl ]. (s1 =~ re) ifMatched: [ :b \| 'Strangely matched!' displayNl ] ifNotMatched: [ 'no match!' displayNl ]. (s replacingRegex: re with: 'modified') displayNl.
http://rosettacode.org/wiki/Regular_expressions	Regular expressions	Task match a string against a regular expression substitute part of a string using a regular expression	#SNOBOL4	SNOBOL4	label subject pattern = object :(goto)
http://rosettacode.org/wiki/Reverse_a_string	Reverse a string	Task Take a string and reverse it. For example, "asdf" becomes "fdsa". Extra credit Preserve Unicode combining characters. For example, "as⃝df̅" becomes "f̅ds⃝a", not "̅fd⃝sa". Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet	#Eiffel	Eiffel	class APPLICATION create make feature make -- Demonstrate string reversal. do my_string := "Hello World!" my_string.mirror print (my_string) end my_string: STRING -- Used for reversal end
http://rosettacode.org/wiki/Reverse_words_in_a_string	Reverse words in a string	Task Reverse the order of all tokens in each of a number of strings and display the result; the order of characters within a token should not be modified. Example Hey you, Bub! would be shown reversed as: Bub! you, Hey Tokens are any non-space characters separated by spaces (formally, white-space); the visible punctuation form part of the word within which it is located and should not be modified. You may assume that there are no significant non-visible characters in the input. Multiple or superfluous spaces may be compressed into a single space. Some strings have no tokens, so an empty string (or one just containing spaces) would be the result. Display the strings in order (1st, 2nd, 3rd, ···), and one string per line. (You can consider the ten strings as ten lines, and the tokens as words.) Input data (ten lines within the box) line ╔════════════════════════════════════════╗ 1 ║ ---------- Ice and Fire ------------ ║ 2 ║ ║ ◄─── a blank line here. 3 ║ fire, in end will world the say Some ║ 4 ║ ice. in say Some ║ 5 ║ desire of tasted I've what From ║ 6 ║ fire. favor who those with hold I ║ 7 ║ ║ ◄─── a blank line here. 8 ║ ... elided paragraph last ... ║ 9 ║ ║ ◄─── a blank line here. 10 ║ Frost Robert ----------------------- ║ ╚════════════════════════════════════════╝ Cf. Phrase reversals	#Sidef	Sidef	DATA.each{\|line\| line.words.reverse.join(" ").say}; __DATA__ ---------- Ice and Fire ------------ fire, in end will world the say Some ice. in say Some desire of tasted I've what From fire. favor who those with hold I ... elided paragraph last ... Frost Robert -----------------------
http://rosettacode.org/wiki/Rot-13	Rot-13	Task Implement a rot-13 function (or procedure, class, subroutine, or other "callable" object as appropriate to your programming environment). Optionally wrap this function in a utility program (like tr, which acts like a common UNIX utility, performing a line-by-line rot-13 encoding of every line of input contained in each file listed on its command line, or (if no filenames are passed thereon) acting as a filter on its "standard input." (A number of UNIX scripting languages and utilities, such as awk and sed either default to processing files in this way or have command line switches or modules to easily implement these wrapper semantics, e.g., Perl and Python). The rot-13 encoding is commonly known from the early days of Usenet "Netnews" as a way of obfuscating text to prevent casual reading of spoiler or potentially offensive material. Many news reader and mail user agent programs have built-in rot-13 encoder/decoders or have the ability to feed a message through any external utility script for performing this (or other) actions. The definition of the rot-13 function is to simply replace every letter of the ASCII alphabet with the letter which is "rotated" 13 characters "around" the 26 letter alphabet from its normal cardinal position (wrapping around from z to a as necessary). Thus the letters abc become nop and so on. Technically rot-13 is a "mono-alphabetic substitution cipher" with a trivial "key". A proper implementation should work on upper and lower case letters, preserve case, and pass all non-alphabetic characters in the input stream through without alteration. Related tasks Caesar cipher Substitution Cipher Vigenère Cipher/Cryptanalysis Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet	#Whenever	Whenever	1 2#read()-N(2); 2 2; 3 defer(1 \|\| N(2) > 90 \|\| N(2) < 65) 5#65-N(5); 4 defer(1 \|\| N(2) > 122 \|\| N(2) < 97) 5#97-N(5); 5 5; 6 defer(3 && 4) put(U(((N(2) - N(5) + 13) % 26) + N(5))); 7 defer(1 \|\| N(2) > 64 \|\| N(2) == 0) put(U(N(2))); 8 again(8) defer(6 && 7) 1,-6#N(6)-1,-7#N(7)-1,-3#N(3)-1,-4#N(4)-1; 9 defer(1 \|\| N(2) != 0) -3,-4,-5#N(5),-6,-7,-8; 10 defer(1 \|\| 9) put("\n");
http://rosettacode.org/wiki/Roman_numerals/Encode	Roman numerals/Encode	Task Create a function taking a positive integer as its parameter and returning a string containing the Roman numeral representation of that integer. Modern Roman numerals are written by expressing each digit separately, starting with the left most digit and skipping any digit with a value of zero. In Roman numerals: 1990 is rendered: 1000=M, 900=CM, 90=XC; resulting in MCMXC 2008 is written as 2000=MM, 8=VIII; or MMVIII 1666 uses each Roman symbol in descending order: MDCLXVI	#VBA	VBA	Private Function roman(n As Integer) As String roman = WorksheetFunction.roman(n) End Function Public Sub main() s = [{10, 2016, 800, 2769, 1666, 476, 1453}] For Each x In s Debug.Print roman(CInt(x)); " "; Next x End Sub
http://rosettacode.org/wiki/Repeat_a_string	Repeat a string	Take a string and repeat it some number of times. Example: repeat("ha", 5) => "hahahahaha" If there is a simpler/more efficient way to repeat a single “character” (i.e. creating a string filled with a certain character), you might want to show that as well (i.e. repeat-char("", 5) => "****"). Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet	#LiveCode	LiveCode	on mouseUp put repeatString("ha", 5) end mouseUp function repeatString str n repeat n times put str after t end repeat return t end repeatString
http://rosettacode.org/wiki/Repeat_a_string	Repeat a string	Take a string and repeat it some number of times. Example: repeat("ha", 5) => "hahahahaha" If there is a simpler/more efficient way to repeat a single “character” (i.e. creating a string filled with a certain character), you might want to show that as well (i.e. repeat-char("", 5) => "****"). Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet	#Logo	Logo	to copies :n :thing [:acc "\|\|] if :n = 0 [output :acc] output (copies :n-1 :thing combine :acc :thing) end
http://rosettacode.org/wiki/Return_multiple_values	Return multiple values	Task Show how to return more than one value from a function.	#XPL0	XPL0	include c:\cxpl\codes; \intrinsic 'code' declarations proc Rect2Polar(X,Y,A,D); \Return two polar coordinate values real X,Y,A,D; [A(0):= ATan2(Y,X); D(0):= Sqrt(XX+YY); ]; \Rect2Polar real Ang, Dist; [Rect2Polar(4.0, 3.0, @Ang, @Dist); \("@" is a new feature similar to 'addr') RlOut(0, Ang); RlOut(0, Dist); CrLf(0); ]
http://rosettacode.org/wiki/Return_multiple_values	Return multiple values	Task Show how to return more than one value from a function.	#Z80_Assembly	Z80 Assembly	foo: ld hl,&ABCD ld bc,&FFFF ret
http://rosettacode.org/wiki/Remove_duplicate_elements	Remove duplicate elements	Sorting Algorithm This is a sorting algorithm. It may be applied to a set of data in order to sort it. For comparing various sorts, see compare sorts. For other sorting algorithms, see sorting algorithms, or: O(n logn) sorts Heap sort \| Merge sort \| Patience sort \| Quick sort O(n log2n) sorts Shell Sort O(n2) sorts Bubble sort \| Cocktail sort \| Cocktail sort with shifting bounds \| Comb sort \| Cycle sort \| Gnome sort \| Insertion sort \| Selection sort \| Strand sort other sorts Bead sort \| Bogo sort \| Common sorted list \| Composite structures sort \| Custom comparator sort \| Counting sort \| Disjoint sublist sort \| External sort \| Jort sort \| Lexicographical sort \| Natural sorting \| Order by pair comparisons \| Order disjoint list items \| Order two numerical lists \| Object identifier (OID) sort \| Pancake sort \| Quickselect \| Permutation sort \| Radix sort \| Ranking methods \| Remove duplicate elements \| Sleep sort \| Stooge sort \| [Sort letters of a string] \| Three variable sort \| Topological sort \| Tree sort Given an Array, derive a sequence of elements in which all duplicates are removed. There are basically three approaches seen here: Put the elements into a hash table which does not allow duplicates. The complexity is O(n) on average, and O(n2) worst case. This approach requires a hash function for your type (which is compatible with equality), either built-in to your language, or provided by the user. Sort the elements and remove consecutive duplicate elements. The complexity of the best sorting algorithms is O(n log n). This approach requires that your type be "comparable", i.e., have an ordering. Putting the elements into a self-balancing binary search tree is a special case of sorting. Go through the list, and for each element, check the rest of the list to see if it appears again, and discard it if it does. The complexity is O(n2). The up-shot is that this always works on any type (provided that you can test for equality).	#J	J	~. 4 3 2 8 0 1 9 5 1 7 6 3 9 9 4 2 1 5 3 2 4 3 2 8 0 1 9 5 7 6 ~. 'chthonic eleemosynary paronomasiac' chtoni elmsyarp
http://rosettacode.org/wiki/Reduced_row_echelon_form	Reduced row echelon form	Reduced row echelon form You are encouraged to solve this task according to the task description, using any language you may know. Task Show how to compute the reduced row echelon form (a.k.a. row canonical form) of a matrix. The matrix can be stored in any datatype that is convenient (for most languages, this will probably be a two-dimensional array). Built-in functions or this pseudocode (from Wikipedia) may be used: function ToReducedRowEchelonForm(Matrix M) is lead := 0 rowCount := the number of rows in M columnCount := the number of columns in M for 0 ≤ r < rowCount do if columnCount ≤ lead then stop end if i = r while M[i, lead] = 0 do i = i + 1 if rowCount = i then i = r lead = lead + 1 if columnCount = lead then stop end if end if end while Swap rows i and r If M[r, lead] is not 0 divide row r by M[r, lead] for 0 ≤ i < rowCount do if i ≠ r do Subtract M[i, lead] multiplied by row r from row i end if end for lead = lead + 1 end for end function For testing purposes, the RREF of this matrix: 1 2 -1 -4 2 3 -1 -11 -2 0 -3 22 is: 1 0 0 -8 0 1 0 1 0 0 1 -2	#PHP	PHP	<?php function rref($matrix) { $lead = 0; $rowCount = count($matrix); if ($rowCount == 0) return $matrix; $columnCount = 0; if (isset($matrix[0])) { $columnCount = count($matrix[0]); } for ($r = 0; $r < $rowCount; $r++) { if ($lead >= $columnCount) break; { $i = $r; while ($matrix[$i][$lead] == 0) { $i++; if ($i == $rowCount) { $i = $r; $lead++; if ($lead == $columnCount) return $matrix; } } $temp = $matrix[$r]; $matrix[$r] = $matrix[$i]; $matrix[$i] = $temp; } { $lv = $matrix[$r][$lead]; for ($j = 0; $j < $columnCount; $j++) { $matrix[$r][$j] = $matrix[$r][$j] / $lv; } } for ($i = 0; $i < $rowCount; $i++) { if ($i != $r) { $lv = $matrix[$i][$lead]; for ($j = 0; $j < $columnCount; $j++) { $matrix[$i][$j] -= $lv * $matrix[$r][$j]; } } } $lead++; } return $matrix; } ?>
http://rosettacode.org/wiki/Real_constants_and_functions	Real constants and functions	Task Show how to use the following math constants and functions in your language (if not available, note it): e (base of the natural logarithm) π {\displaystyle \pi } square root logarithm (any base allowed) exponential (ex ) absolute value (a.k.a. "magnitude") floor (largest integer less than or equal to this number--not the same as truncate or int) ceiling (smallest integer not less than this number--not the same as round up) power (xy ) Related task Trigonometric Functions	#Maple	Maple	> abs(ceil(floor(ln(exp(1)^sqrt(exp(Pi*I)+1))))); 0
http://rosettacode.org/wiki/Remove_lines_from_a_file	Remove lines from a file	Task Remove a specific line or a number of lines from a file. This should be implemented as a routine that takes three parameters (filename, starting line, and the number of lines to be removed). For the purpose of this task, line numbers and the number of lines start at one, so to remove the first two lines from the file foobar.txt, the parameters should be: foobar.txt, 1, 2 Empty lines are considered and should still be counted, and if the specified line is empty, it should still be removed. An appropriate message should appear if an attempt is made to remove lines beyond the end of the file.	#UNIX_Shell	UNIX Shell	#!/bin/sh error() { echo >&2 "$0: $*" exit 1 } [ $# -ne 3 ] && error "Incorrect number of parameters" file=$1 start=$2 count=$3 end=`expr $start + $count - 1` [ -f "$file" ] \|\| error "$file does not exist" sed "$start,${end}d" "$file" >/tmp/$$ && mv /tmp/$$ "$file"
http://rosettacode.org/wiki/Read_entire_file	Read entire file	Task Load the entire contents of some text file as a single string variable. If applicable, discuss: encoding selection, the possibility of memory-mapping. Of course, in practice one should avoid reading an entire file at once if the file is large and the task can be accomplished incrementally instead (in which case check File IO); this is for those cases where having the entire file is actually what is wanted.	#Nim	Nim	readFile(filename)
http://rosettacode.org/wiki/Read_entire_file	Read entire file	Task Load the entire contents of some text file as a single string variable. If applicable, discuss: encoding selection, the possibility of memory-mapping. Of course, in practice one should avoid reading an entire file at once if the file is large and the task can be accomplished incrementally instead (in which case check File IO); this is for those cases where having the entire file is actually what is wanted.	#Objeck	Objeck	string := FileReader->ReadFile("in.txt");
http://rosettacode.org/wiki/Regular_expressions	Regular expressions	Task match a string against a regular expression substitute part of a string using a regular expression	#Standard_ML	Standard ML	CM.make "$/regexp-lib.cm"; structure RE = RegExpFn ( structure P = AwkSyntax structure E = BackTrackEngine); val re = RE.compileString "string$"; val string = "I am a string"; case StringCvt.scanString (RE.find re) string of NONE => print "match failed\n" \| SOME match => let val {pos, len} = MatchTree.root match in print ("matched at position " ^ Int.toString pos ^ "\n") end;
http://rosettacode.org/wiki/Regular_expressions	Regular expressions	Task match a string against a regular expression substitute part of a string using a regular expression	#Stata	Stata	scalar s="ars longa vita brevis" * is there a vowel? di regexm(s,"[aeiou]") * replace the first vowel with "?" di regexr(s,"[aeiou]","?")
http://rosettacode.org/wiki/Reverse_a_string	Reverse a string	Task Take a string and reverse it. For example, "asdf" becomes "fdsa". Extra credit Preserve Unicode combining characters. For example, "as⃝df̅" becomes "f̅ds⃝a", not "̅fd⃝sa". Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet	#Ela	Ela	reverse_string str = rev len str where len = length str rev 0 str = "" rev n str = toString (str : nn) +> rev nn str where nn = n - 1 reverse_string "Hello"
http://rosettacode.org/wiki/Reverse_words_in_a_string	Reverse words in a string	Task Reverse the order of all tokens in each of a number of strings and display the result; the order of characters within a token should not be modified. Example Hey you, Bub! would be shown reversed as: Bub! you, Hey Tokens are any non-space characters separated by spaces (formally, white-space); the visible punctuation form part of the word within which it is located and should not be modified. You may assume that there are no significant non-visible characters in the input. Multiple or superfluous spaces may be compressed into a single space. Some strings have no tokens, so an empty string (or one just containing spaces) would be the result. Display the strings in order (1st, 2nd, 3rd, ···), and one string per line. (You can consider the ten strings as ten lines, and the tokens as words.) Input data (ten lines within the box) line ╔════════════════════════════════════════╗ 1 ║ ---------- Ice and Fire ------------ ║ 2 ║ ║ ◄─── a blank line here. 3 ║ fire, in end will world the say Some ║ 4 ║ ice. in say Some ║ 5 ║ desire of tasted I've what From ║ 6 ║ fire. favor who those with hold I ║ 7 ║ ║ ◄─── a blank line here. 8 ║ ... elided paragraph last ... ║ 9 ║ ║ ◄─── a blank line here. 10 ║ Frost Robert ----------------------- ║ ╚════════════════════════════════════════╝ Cf. Phrase reversals	#Smalltalk	Smalltalk	poem := '---------- Ice and Fire ------------ fire, in end will world the say Some ice. in say Some desire of tasted I''ve what From fire. favor who those with hold I ... elided paragraph last ... Frost Robert -----------------------'. (poem lines collect: [ :line \| ((line splitOn: ' ') reverse) joinUsing: ' ' ]) joinUsing: (String cr).
http://rosettacode.org/wiki/Reverse_words_in_a_string	Reverse words in a string	Task Reverse the order of all tokens in each of a number of strings and display the result; the order of characters within a token should not be modified. Example Hey you, Bub! would be shown reversed as: Bub! you, Hey Tokens are any non-space characters separated by spaces (formally, white-space); the visible punctuation form part of the word within which it is located and should not be modified. You may assume that there are no significant non-visible characters in the input. Multiple or superfluous spaces may be compressed into a single space. Some strings have no tokens, so an empty string (or one just containing spaces) would be the result. Display the strings in order (1st, 2nd, 3rd, ···), and one string per line. (You can consider the ten strings as ten lines, and the tokens as words.) Input data (ten lines within the box) line ╔════════════════════════════════════════╗ 1 ║ ---------- Ice and Fire ------------ ║ 2 ║ ║ ◄─── a blank line here. 3 ║ fire, in end will world the say Some ║ 4 ║ ice. in say Some ║ 5 ║ desire of tasted I've what From ║ 6 ║ fire. favor who those with hold I ║ 7 ║ ║ ◄─── a blank line here. 8 ║ ... elided paragraph last ... ║ 9 ║ ║ ◄─── a blank line here. 10 ║ Frost Robert ----------------------- ║ ╚════════════════════════════════════════╝ Cf. Phrase reversals	#Sparkling	Sparkling	let lines = split("---------- Ice and Fire ------------ fire, in end will world the say Some ice. in say Some desire of tasted I've what From fire. favor who those with hold I ... elided paragraph last ... Frost Robert -----------------------", "\n"); foreach(lines, function(idx, line) { let words = split(line, " "); let reverseWords = map(words, function(idx) { return words[sizeof words - idx - 1]; }); foreach(reverseWords, function(idx, word) { printf("%s ", word); }); print(); });
http://rosettacode.org/wiki/Rot-13	Rot-13	Task Implement a rot-13 function (or procedure, class, subroutine, or other "callable" object as appropriate to your programming environment). Optionally wrap this function in a utility program (like tr, which acts like a common UNIX utility, performing a line-by-line rot-13 encoding of every line of input contained in each file listed on its command line, or (if no filenames are passed thereon) acting as a filter on its "standard input." (A number of UNIX scripting languages and utilities, such as awk and sed either default to processing files in this way or have command line switches or modules to easily implement these wrapper semantics, e.g., Perl and Python). The rot-13 encoding is commonly known from the early days of Usenet "Netnews" as a way of obfuscating text to prevent casual reading of spoiler or potentially offensive material. Many news reader and mail user agent programs have built-in rot-13 encoder/decoders or have the ability to feed a message through any external utility script for performing this (or other) actions. The definition of the rot-13 function is to simply replace every letter of the ASCII alphabet with the letter which is "rotated" 13 characters "around" the 26 letter alphabet from its normal cardinal position (wrapping around from z to a as necessary). Thus the letters abc become nop and so on. Technically rot-13 is a "mono-alphabetic substitution cipher" with a trivial "key". A proper implementation should work on upper and lower case letters, preserve case, and pass all non-alphabetic characters in the input stream through without alteration. Related tasks Caesar cipher Substitution Cipher Vigenère Cipher/Cryptanalysis Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet	#Whitespace	Whitespace
http://rosettacode.org/wiki/Roman_numerals/Encode	Roman numerals/Encode	Task Create a function taking a positive integer as its parameter and returning a string containing the Roman numeral representation of that integer. Modern Roman numerals are written by expressing each digit separately, starting with the left most digit and skipping any digit with a value of zero. In Roman numerals: 1990 is rendered: 1000=M, 900=CM, 90=XC; resulting in MCMXC 2008 is written as 2000=MM, 8=VIII; or MMVIII 1666 uses each Roman symbol in descending order: MDCLXVI	#Vedit_macro_language	Vedit macro language	// Main program for testing the function // do { #1 = Get_Num("Number to convert: ", STATLINE) Call("NUM_TO_ROMAN") Num_Type(#1, NOCR) Message(" = ") Reg_Type(1) Type_Newline } while (Reg_Size(1)) Return // Convert numeric value into Roman number // #1 = number to convert; on return: T-reg(1) = Roman number // :NUM_TO_ROMAN: Reg_Empty(1) // @1 = Results (Roman number) if (#1 < 1) { Return } // non-positive numbers return empty string Buf_Switch(Buf_Free) Ins_Text("M1000,CM900,D500,CD400,C100,XC90,L50,XL40,X10,IX9,V5,IV4,I1") BOF #2 = #1 Repeat(ALL) { Search("\|A\|[\|A]", ADVANCE+ERRBREAK) // get next item from conversion list Reg_Copy_Block(20, CP-Chars_Matched, CP) // @20 = Letter(s) to be inserted #11 = Num_Eval() // #11 = magnitude (1000...1) while (#2 >= #11) { Reg_Set(1, @20, APPEND) #2 -= #11 } } Buf_Quit(OK) Return
http://rosettacode.org/wiki/Repeat_a_string	Repeat a string	Take a string and repeat it some number of times. Example: repeat("ha", 5) => "hahahahaha" If there is a simpler/more efficient way to repeat a single “character” (i.e. creating a string filled with a certain character), you might want to show that as well (i.e. repeat-char("", 5) => "****"). Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet	#Lua	Lua	function repeats(s, n) return n > 0 and s .. repeats(s, n-1) or "" end
http://rosettacode.org/wiki/Return_multiple_values	Return multiple values	Task Show how to return more than one value from a function.	#zkl	zkl	fcn f{return(1,2,"three")} a,b,c:=f() // a==1, b==2, c=="three"
http://rosettacode.org/wiki/Remove_duplicate_elements	Remove duplicate elements	Sorting Algorithm This is a sorting algorithm. It may be applied to a set of data in order to sort it. For comparing various sorts, see compare sorts. For other sorting algorithms, see sorting algorithms, or: O(n logn) sorts Heap sort \| Merge sort \| Patience sort \| Quick sort O(n log2n) sorts Shell Sort O(n2) sorts Bubble sort \| Cocktail sort \| Cocktail sort with shifting bounds \| Comb sort \| Cycle sort \| Gnome sort \| Insertion sort \| Selection sort \| Strand sort other sorts Bead sort \| Bogo sort \| Common sorted list \| Composite structures sort \| Custom comparator sort \| Counting sort \| Disjoint sublist sort \| External sort \| Jort sort \| Lexicographical sort \| Natural sorting \| Order by pair comparisons \| Order disjoint list items \| Order two numerical lists \| Object identifier (OID) sort \| Pancake sort \| Quickselect \| Permutation sort \| Radix sort \| Ranking methods \| Remove duplicate elements \| Sleep sort \| Stooge sort \| [Sort letters of a string] \| Three variable sort \| Topological sort \| Tree sort Given an Array, derive a sequence of elements in which all duplicates are removed. There are basically three approaches seen here: Put the elements into a hash table which does not allow duplicates. The complexity is O(n) on average, and O(n2) worst case. This approach requires a hash function for your type (which is compatible with equality), either built-in to your language, or provided by the user. Sort the elements and remove consecutive duplicate elements. The complexity of the best sorting algorithms is O(n log n). This approach requires that your type be "comparable", i.e., have an ordering. Putting the elements into a self-balancing binary search tree is a special case of sorting. Go through the list, and for each element, check the rest of the list to see if it appears again, and discard it if it does. The complexity is O(n2). The up-shot is that this always works on any type (provided that you can test for equality).	#Java	Java	import java.util.*; class Test { public static void main(String[] args) { Object[] data = {1, 1, 2, 2, 3, 3, 3, "a", "a", "b", "b", "c", "d"}; Set<Object> uniqueSet = new HashSet<Object>(Arrays.asList(data)); for (Object o : uniqueSet) System.out.printf("%s ", o); } }
http://rosettacode.org/wiki/Reduced_row_echelon_form	Reduced row echelon form	Reduced row echelon form You are encouraged to solve this task according to the task description, using any language you may know. Task Show how to compute the reduced row echelon form (a.k.a. row canonical form) of a matrix. The matrix can be stored in any datatype that is convenient (for most languages, this will probably be a two-dimensional array). Built-in functions or this pseudocode (from Wikipedia) may be used: function ToReducedRowEchelonForm(Matrix M) is lead := 0 rowCount := the number of rows in M columnCount := the number of columns in M for 0 ≤ r < rowCount do if columnCount ≤ lead then stop end if i = r while M[i, lead] = 0 do i = i + 1 if rowCount = i then i = r lead = lead + 1 if columnCount = lead then stop end if end if end while Swap rows i and r If M[r, lead] is not 0 divide row r by M[r, lead] for 0 ≤ i < rowCount do if i ≠ r do Subtract M[i, lead] multiplied by row r from row i end if end for lead = lead + 1 end for end function For testing purposes, the RREF of this matrix: 1 2 -1 -4 2 3 -1 -11 -2 0 -3 22 is: 1 0 0 -8 0 1 0 1 0 0 1 -2	#PicoLisp	PicoLisp	(de reducedRowEchelonForm (Mat) (let (Lead 1 Cols (length (car Mat))) (for (X Mat X (cdr X)) (NIL (loop (T (seek '((R) (n0 (get R 1 Lead))) X) @ ) (T (> (inc 'Lead) Cols)) ) ) (xchg @ X) (let D (get X 1 Lead) (map '((R) (set R (/ (car R) D))) (car X) ) ) (for Y Mat (unless (== Y (car X)) (let N (- (get Y Lead)) (map '((Dst Src) (inc Dst (* N (car Src))) ) Y (car X) ) ) ) ) (T (> (inc 'Lead) Cols)) ) ) Mat )
http://rosettacode.org/wiki/Real_constants_and_functions	Real constants and functions	Task Show how to use the following math constants and functions in your language (if not available, note it): e (base of the natural logarithm) π {\displaystyle \pi } square root logarithm (any base allowed) exponential (ex ) absolute value (a.k.a. "magnitude") floor (largest integer less than or equal to this number--not the same as truncate or int) ceiling (smallest integer not less than this number--not the same as round up) power (xy ) Related task Trigonometric Functions	#Mathematica.2FWolfram_Language	Mathematica/Wolfram Language	E Pi Sqrt[x] Log[x] Log[b,x] Exp[x] Abs[x] Floor[x] Ceiling[x] Power[x, y]
http://rosettacode.org/wiki/Real_constants_and_functions	Real constants and functions	Task Show how to use the following math constants and functions in your language (if not available, note it): e (base of the natural logarithm) π {\displaystyle \pi } square root logarithm (any base allowed) exponential (ex ) absolute value (a.k.a. "magnitude") floor (largest integer less than or equal to this number--not the same as truncate or int) ceiling (smallest integer not less than this number--not the same as round up) power (xy ) Related task Trigonometric Functions	#MATLAB_.2F_Octave	MATLAB / Octave	exp(1) % e pi % pi sqrt(x) % square root log(x) % natural logarithm log2(x) % logarithm base 2 log10(x) % logarithm base 10 exp(x) % exponential abs(-x) % absolute value floor(x) % floor ceil(x) % ceiling x^y % power
http://rosettacode.org/wiki/Remove_lines_from_a_file	Remove lines from a file	Task Remove a specific line or a number of lines from a file. This should be implemented as a routine that takes three parameters (filename, starting line, and the number of lines to be removed). For the purpose of this task, line numbers and the number of lines start at one, so to remove the first two lines from the file foobar.txt, the parameters should be: foobar.txt, 1, 2 Empty lines are considered and should still be counted, and if the specified line is empty, it should still be removed. An appropriate message should appear if an attempt is made to remove lines beyond the end of the file.	#VBA	VBA	Option Explicit Sub Main() 'See Output #1 RemoveLines "C:\Users\" & Environ("username") & "\Desktop\foobar.txt", 11, 5 'See Output #2 RemoveLines "C:\Users\" & Environ("username") & "\Desktop\foobar.txt", 8, 5 'See Output #3 RemoveLines "C:\Users\" & Environ("username") & "\Desktop\foobar.txt", 3, 5 End Sub Private Sub RemoveLines(StrFile As String, StartLine As Long, NumberOfLines As Long) Dim Nb As Integer, s As String, count As Long, out As String Nb = FreeFile Open StrFile For Input As #Nb While Not EOF(Nb) count = count + 1 Line Input #Nb, s If count < StartLine Or count >= StartLine + NumberOfLines Then out = out & s & vbCrLf End If Wend Close #Nb If StartLine >= count Then MsgBox "The file contains only " & count & " lines" ElseIf StartLine + NumberOfLines > count Then MsgBox "You only can remove " & count - StartLine & " lines" Else Nb = FreeFile Open StrFile For Output As #Nb Print #Nb, out Close #Nb End If End Sub
http://rosettacode.org/wiki/Read_entire_file	Read entire file	Task Load the entire contents of some text file as a single string variable. If applicable, discuss: encoding selection, the possibility of memory-mapping. Of course, in practice one should avoid reading an entire file at once if the file is large and the task can be accomplished incrementally instead (in which case check File IO); this is for those cases where having the entire file is actually what is wanted.	#Objective-C	Objective-C	/*** 0. PREPARATION / // We need a text file to read; let's redirect a C string to a new file // using the shell by way of the stdlib system() function. system ("echo \"Hello, World!\" > ~/HelloRosetta"); /** 1. THE TASK / // Instantiate an NSString which describes the filesystem location of // the file we will be reading. NSString filePath = [NSHomeDirectory() stringByAppendingPathComponent:@"HelloRosetta"]; // The selector we're going to use to complete this task, // stringWithContentsOfFile:encoding:error, has an optional `error' // parameter which can be used to return information about any // errors it might run into. It's optional, but we'll create an NSError // anyways to demonstrate best practice. NSError anError; // And finally, the task: read and store the contents of a file as an // NSString. NSString aString = [NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:&anError]; // If the file read was unsuccessful, display the error description. // Otherwise, display the NSString. if (!aString) { NSLog(@"%@", [anError localizedDescription]); } else { NSLog(@"%@", aString); }
http://rosettacode.org/wiki/Read_entire_file	Read entire file	Task Load the entire contents of some text file as a single string variable. If applicable, discuss: encoding selection, the possibility of memory-mapping. Of course, in practice one should avoid reading an entire file at once if the file is large and the task can be accomplished incrementally instead (in which case check File IO); this is for those cases where having the entire file is actually what is wanted.	#OCaml	OCaml	let load_file f = let ic = open_in f in let n = in_channel_length ic in let s = Bytes.create n in really_input ic s 0 n; close_in ic; (s)
http://rosettacode.org/wiki/Regular_expressions	Regular expressions	Task match a string against a regular expression substitute part of a string using a regular expression	#Swift	Swift	import Foundation let str = "I am a string" if let range = str.rangeOfString("string$", options: .RegularExpressionSearch) { println("Ends with 'string'") }
http://rosettacode.org/wiki/Regular_expressions	Regular expressions	Task match a string against a regular expression substitute part of a string using a regular expression	#Tcl	Tcl	set theString "I am a string" if {[regexp -- {string$} $theString]} { puts "Ends with 'string'" } if {![regexp -- {^You} $theString]} { puts "Does not start with 'You'" }
http://rosettacode.org/wiki/Reverse_a_string	Reverse a string	Task Take a string and reverse it. For example, "asdf" becomes "fdsa". Extra credit Preserve Unicode combining characters. For example, "as⃝df̅" becomes "f̅ds⃝a", not "̅fd⃝sa". Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet	#Elena	Elena	import system'routines; import extensions; import extensions'text; extension extension { reversedLiteral() = self.toArray().sequenceReverse().summarize(new StringWriter()); } public program() { console.printLine("Hello World".reversedLiteral()) }
http://rosettacode.org/wiki/Reverse_words_in_a_string	Reverse words in a string	Task Reverse the order of all tokens in each of a number of strings and display the result; the order of characters within a token should not be modified. Example Hey you, Bub! would be shown reversed as: Bub! you, Hey Tokens are any non-space characters separated by spaces (formally, white-space); the visible punctuation form part of the word within which it is located and should not be modified. You may assume that there are no significant non-visible characters in the input. Multiple or superfluous spaces may be compressed into a single space. Some strings have no tokens, so an empty string (or one just containing spaces) would be the result. Display the strings in order (1st, 2nd, 3rd, ···), and one string per line. (You can consider the ten strings as ten lines, and the tokens as words.) Input data (ten lines within the box) line ╔════════════════════════════════════════╗ 1 ║ ---------- Ice and Fire ------------ ║ 2 ║ ║ ◄─── a blank line here. 3 ║ fire, in end will world the say Some ║ 4 ║ ice. in say Some ║ 5 ║ desire of tasted I've what From ║ 6 ║ fire. favor who those with hold I ║ 7 ║ ║ ◄─── a blank line here. 8 ║ ... elided paragraph last ... ║ 9 ║ ║ ◄─── a blank line here. 10 ║ Frost Robert ----------------------- ║ ╚════════════════════════════════════════╝ Cf. Phrase reversals	#Standard_ML	Standard ML	val lines = [ " ---------- Ice and Fire ------------ ", " ", " fire, in end will world the say Some ", " ice. in say Some ", " desire of tasted I've what From ", " fire. favor who those with hold I ", " ", " ... elided paragraph last ... ", " ", " Frost Robert ----------------------- " ] val revWords = String.concatWith " " o rev o String.tokens Char.isSpace val () = app (fn line => print (revWords line ^ "\n")) lines
http://rosettacode.org/wiki/Reverse_words_in_a_string	Reverse words in a string	Task Reverse the order of all tokens in each of a number of strings and display the result; the order of characters within a token should not be modified. Example Hey you, Bub! would be shown reversed as: Bub! you, Hey Tokens are any non-space characters separated by spaces (formally, white-space); the visible punctuation form part of the word within which it is located and should not be modified. You may assume that there are no significant non-visible characters in the input. Multiple or superfluous spaces may be compressed into a single space. Some strings have no tokens, so an empty string (or one just containing spaces) would be the result. Display the strings in order (1st, 2nd, 3rd, ···), and one string per line. (You can consider the ten strings as ten lines, and the tokens as words.) Input data (ten lines within the box) line ╔════════════════════════════════════════╗ 1 ║ ---------- Ice and Fire ------------ ║ 2 ║ ║ ◄─── a blank line here. 3 ║ fire, in end will world the say Some ║ 4 ║ ice. in say Some ║ 5 ║ desire of tasted I've what From ║ 6 ║ fire. favor who those with hold I ║ 7 ║ ║ ◄─── a blank line here. 8 ║ ... elided paragraph last ... ║ 9 ║ ║ ◄─── a blank line here. 10 ║ Frost Robert ----------------------- ║ ╚════════════════════════════════════════╝ Cf. Phrase reversals	#Swift	Swift	import Foundation // convenience extension for better clarity extension String { var lines: [String] { get { return self.componentsSeparatedByCharactersInSet(NSCharacterSet.newlineCharacterSet()) } } var words: [String] { get { return self.componentsSeparatedByCharactersInSet(NSCharacterSet.whitespaceCharacterSet()) } } } let input = "---------- Ice and Fire ------------\n\nfire, in end will world the say Some\nice. in say Some\ndesire of tasted I've what From\nfire. favor who those with hold I\n\n... elided paragraph last ...\n\nFrost Robert -----------------------\n" let output = input.lines.map { $0.words.reverse().joinWithSeparator(" ") }.joinWithSeparator("\n") print(output)
http://rosettacode.org/wiki/Rot-13	Rot-13	Task Implement a rot-13 function (or procedure, class, subroutine, or other "callable" object as appropriate to your programming environment). Optionally wrap this function in a utility program (like tr, which acts like a common UNIX utility, performing a line-by-line rot-13 encoding of every line of input contained in each file listed on its command line, or (if no filenames are passed thereon) acting as a filter on its "standard input." (A number of UNIX scripting languages and utilities, such as awk and sed either default to processing files in this way or have command line switches or modules to easily implement these wrapper semantics, e.g., Perl and Python). The rot-13 encoding is commonly known from the early days of Usenet "Netnews" as a way of obfuscating text to prevent casual reading of spoiler or potentially offensive material. Many news reader and mail user agent programs have built-in rot-13 encoder/decoders or have the ability to feed a message through any external utility script for performing this (or other) actions. The definition of the rot-13 function is to simply replace every letter of the ASCII alphabet with the letter which is "rotated" 13 characters "around" the 26 letter alphabet from its normal cardinal position (wrapping around from z to a as necessary). Thus the letters abc become nop and so on. Technically rot-13 is a "mono-alphabetic substitution cipher" with a trivial "key". A proper implementation should work on upper and lower case letters, preserve case, and pass all non-alphabetic characters in the input stream through without alteration. Related tasks Caesar cipher Substitution Cipher Vigenère Cipher/Cryptanalysis Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet	#Wren	Wren	var rot13 = Fn.new { \|s\| var bytes = s.bytes.toList for (i in 0...bytes.count) { var c = bytes[i] if ((c >= 65 && c <= 77) \|\| (c >= 97 && c <= 109)) { bytes[i] = c + 13 } else if ((c >= 78 && c <= 90) \|\| (c >= 110 && c <= 122)) { bytes[i] = c - 13 } } return bytes.map { \|b\| String.fromByte(b) }.join() } System.print(rot13.call("nowhere ABJURER"))
http://rosettacode.org/wiki/Roman_numerals/Encode	Roman numerals/Encode	Task Create a function taking a positive integer as its parameter and returning a string containing the Roman numeral representation of that integer. Modern Roman numerals are written by expressing each digit separately, starting with the left most digit and skipping any digit with a value of zero. In Roman numerals: 1990 is rendered: 1000=M, 900=CM, 90=XC; resulting in MCMXC 2008 is written as 2000=MM, 8=VIII; or MMVIII 1666 uses each Roman symbol in descending order: MDCLXVI	#Visual_Basic	Visual Basic	Function toRoman(value) As String Dim arabic As Variant Dim roman As Variant arabic = Array(1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1) roman = Array("M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I") Dim i As Integer, result As String For i = 0 To 12 Do While value >= arabic(i) result = result + roman(i) value = value - arabic(i) Loop Next i toRoman = result End Function Sub Main() MsgBox toRoman(Val(InputBox("Number, please"))) End Sub
http://rosettacode.org/wiki/Repeat_a_string	Repeat a string	Take a string and repeat it some number of times. Example: repeat("ha", 5) => "hahahahaha" If there is a simpler/more efficient way to repeat a single “character” (i.e. creating a string filled with a certain character), you might want to show that as well (i.e. repeat-char("", 5) => "****"). Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet	#Maple	Maple	> use StringTools in > Repeat( "abc", 10 ); # repeat an arbitrary string > Fill( "x", 20 ) # repeat a character > end use; "abcabcabcabcabcabcabcabcabcabc" "xxxxxxxxxxxxxxxxxxxx"
http://rosettacode.org/wiki/Repeat_a_string	Repeat a string	Take a string and repeat it some number of times. Example: repeat("ha", 5) => "hahahahaha" If there is a simpler/more efficient way to repeat a single “character” (i.e. creating a string filled with a certain character), you might want to show that as well (i.e. repeat-char("", 5) => "****"). Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet	#Mathematica.2FWolfram_Language	Mathematica/Wolfram Language	(* solution 1 ) rep[n_Integer,s_String]:=Apply[StringJoin,ConstantArray[s,{n}]] ( solution 2 -- @@ is the infix form of Apply[] ) rep[n_Integer,s_String]:=StringJoin@@Table[s,{n}] ( solution 3 -- demonstrating another of the large number of looping constructs available *) rep[n_Integer,s_String]:=Nest[StringJoin[s, #] &,s,n-1]
http://rosettacode.org/wiki/Remove_duplicate_elements	Remove duplicate elements	Sorting Algorithm This is a sorting algorithm. It may be applied to a set of data in order to sort it. For comparing various sorts, see compare sorts. For other sorting algorithms, see sorting algorithms, or: O(n logn) sorts Heap sort \| Merge sort \| Patience sort \| Quick sort O(n log2n) sorts Shell Sort O(n2) sorts Bubble sort \| Cocktail sort \| Cocktail sort with shifting bounds \| Comb sort \| Cycle sort \| Gnome sort \| Insertion sort \| Selection sort \| Strand sort other sorts Bead sort \| Bogo sort \| Common sorted list \| Composite structures sort \| Custom comparator sort \| Counting sort \| Disjoint sublist sort \| External sort \| Jort sort \| Lexicographical sort \| Natural sorting \| Order by pair comparisons \| Order disjoint list items \| Order two numerical lists \| Object identifier (OID) sort \| Pancake sort \| Quickselect \| Permutation sort \| Radix sort \| Ranking methods \| Remove duplicate elements \| Sleep sort \| Stooge sort \| [Sort letters of a string] \| Three variable sort \| Topological sort \| Tree sort Given an Array, derive a sequence of elements in which all duplicates are removed. There are basically three approaches seen here: Put the elements into a hash table which does not allow duplicates. The complexity is O(n) on average, and O(n2) worst case. This approach requires a hash function for your type (which is compatible with equality), either built-in to your language, or provided by the user. Sort the elements and remove consecutive duplicate elements. The complexity of the best sorting algorithms is O(n log n). This approach requires that your type be "comparable", i.e., have an ordering. Putting the elements into a self-balancing binary search tree is a special case of sorting. Go through the list, and for each element, check the rest of the list to see if it appears again, and discard it if it does. The complexity is O(n2). The up-shot is that this always works on any type (provided that you can test for equality).	#JavaScript	JavaScript	function unique(ary) { // concat() with no args is a way to clone an array var u = ary.concat().sort(); for (var i = 1; i < u.length; ) { if (u[i-1] === u[i]) u.splice(i,1); else i++; } return u; } var ary = [1, 2, 3, "a", "b", "c", 2, 3, 4, "b", "c", "d", "4"]; var uniq = unique(ary); for (var i = 0; i < uniq.length; i++) print(uniq[i] + "\t" + typeof(uniq[i]));
http://rosettacode.org/wiki/Reduced_row_echelon_form	Reduced row echelon form	Reduced row echelon form You are encouraged to solve this task according to the task description, using any language you may know. Task Show how to compute the reduced row echelon form (a.k.a. row canonical form) of a matrix. The matrix can be stored in any datatype that is convenient (for most languages, this will probably be a two-dimensional array). Built-in functions or this pseudocode (from Wikipedia) may be used: function ToReducedRowEchelonForm(Matrix M) is lead := 0 rowCount := the number of rows in M columnCount := the number of columns in M for 0 ≤ r < rowCount do if columnCount ≤ lead then stop end if i = r while M[i, lead] = 0 do i = i + 1 if rowCount = i then i = r lead = lead + 1 if columnCount = lead then stop end if end if end while Swap rows i and r If M[r, lead] is not 0 divide row r by M[r, lead] for 0 ≤ i < rowCount do if i ≠ r do Subtract M[i, lead] multiplied by row r from row i end if end for lead = lead + 1 end for end function For testing purposes, the RREF of this matrix: 1 2 -1 -4 2 3 -1 -11 -2 0 -3 22 is: 1 0 0 -8 0 1 0 1 0 0 1 -2	#Python	Python	def ToReducedRowEchelonForm( M): if not M: return lead = 0 rowCount = len(M) columnCount = len(M[0]) for r in range(rowCount): if lead >= columnCount: return i = r while M[i][lead] == 0: i += 1 if i == rowCount: i = r lead += 1 if columnCount == lead: return M[i],M[r] = M[r],M[i] lv = M[r][lead] M[r] = [ mrx / float(lv) for mrx in M[r]] for i in range(rowCount): if i != r: lv = M[i][lead] M[i] = [ iv - lv*rv for rv,iv in zip(M[r],M[i])] lead += 1 mtx = [ [ 1, 2, -1, -4], [ 2, 3, -1, -11], [-2, 0, -3, 22],] ToReducedRowEchelonForm( mtx ) for rw in mtx: print ', '.join( (str(rv) for rv in rw) )
http://rosettacode.org/wiki/Real_constants_and_functions	Real constants and functions	Task Show how to use the following math constants and functions in your language (if not available, note it): e (base of the natural logarithm) π {\displaystyle \pi } square root logarithm (any base allowed) exponential (ex ) absolute value (a.k.a. "magnitude") floor (largest integer less than or equal to this number--not the same as truncate or int) ceiling (smallest integer not less than this number--not the same as round up) power (xy ) Related task Trigonometric Functions	#MAXScript	MAXScript	e -- Euler's number pi -- pi log x -- natural logarithm log10 x -- log base 10 exp x -- exponantial abs x -- absolute value floor x -- floor ceil x -- ceiling pow x y -- power
http://rosettacode.org/wiki/Real_constants_and_functions	Real constants and functions	Task Show how to use the following math constants and functions in your language (if not available, note it): e (base of the natural logarithm) π {\displaystyle \pi } square root logarithm (any base allowed) exponential (ex ) absolute value (a.k.a. "magnitude") floor (largest integer less than or equal to this number--not the same as truncate or int) ceiling (smallest integer not less than this number--not the same as round up) power (xy ) Related task Trigonometric Functions	#Mercury	Mercury	math.pi % Pi. math.e % Euler's number. math.sqrt(X) % Square root of X. math.ln(X) % Natural logarithm of X. math.log10(X) % Logarithm to the base 10 of X. math.log2(X) % Logarithm to the base 2 of X. math.log(B, X) % Logarithm to the base B of X. math.exp(X) % e raised to the power of X. float.abs(X) % Absolute value of X. math.floor(X) % Floor of X. math.ceiling(X) % Ceiling of X. math.pow(X, Y) % X raised to the power of Y.
http://rosettacode.org/wiki/Remove_lines_from_a_file	Remove lines from a file	Task Remove a specific line or a number of lines from a file. This should be implemented as a routine that takes three parameters (filename, starting line, and the number of lines to be removed). For the purpose of this task, line numbers and the number of lines start at one, so to remove the first two lines from the file foobar.txt, the parameters should be: foobar.txt, 1, 2 Empty lines are considered and should still be counted, and if the specified line is empty, it should still be removed. An appropriate message should appear if an attempt is made to remove lines beyond the end of the file.	#VBScript	VBScript	Sub remove_lines(filepath,start,number) Set objFSO = CreateObject("Scripting.FileSystemObject") Set InFile = objFSO.OpenTextFile(filepath,1,False) line_count = 1 discard_count = 1 out_txt = "" Do Until InFile.AtEndOfStream line = InFile.ReadLine If line_count <> start Then If InFile.AtEndOfStream = False Then out_txt = out_txt & line & vbCrLf Else out_txt = out_txt & line End If line_count = line_count + 1 Else Do Until discard_count = number InFile.SkipLine discard_count = discard_count + 1 Loop line_count = line_count + 1 End If Loop InFile.Close Set OutFile = objFSO.OpenTextFile(filepath,2,False) OutFile.Write(out_txt) OutFile.Close Set objFSO = Nothing End Sub Call remove_lines("C:\Test.txt",3,4)
http://rosettacode.org/wiki/Remove_lines_from_a_file	Remove lines from a file	Task Remove a specific line or a number of lines from a file. This should be implemented as a routine that takes three parameters (filename, starting line, and the number of lines to be removed). For the purpose of this task, line numbers and the number of lines start at one, so to remove the first two lines from the file foobar.txt, the parameters should be: foobar.txt, 1, 2 Empty lines are considered and should still be counted, and if the specified line is empty, it should still be removed. An appropriate message should appear if an attempt is made to remove lines beyond the end of the file.	#Wren	Wren	import "os" for Platform import "io" for File var removeLines = Fn.new { \|fileName, startLine, numLines\| if (fileName == "" \|\| startLine < 1 \|\| numLines < 1) Fiber.abort("Invalid argument(s).") if (!File.exists(fileName)) Fiber.abort("Can't find %(fileName).") var text = File.read(fileName) System.print("Contents of %(fileName) before removal:\n%(text)") var sep = Platform.isWindows ? "\r\n" : "\n" var lines = text.split(sep) var size = lines.count if (startLine > size) { System.print("The starting line is beyond the length of the file.") return } var n = numLines if (startLine + numLines - 1 > size) { System.print("Attempting to remove some lines which are beyond the end of the file.") n = size - startLine + 1 } lines = lines.take(startLine - 1).toList + lines.skip(startLine + n - 1).toList text = lines.join(sep) File.create(fileName) { \|file\| // effectively overwrites the file file.writeBytes(text) } System.print("Contents of %(fileName) after removal of %(numLines) lines starting from line %(startLine):") System.print(File.read(fileName)) } removeLines.call("foobar.txt", 2, 3)
http://rosettacode.org/wiki/Read_entire_file	Read entire file	Task Load the entire contents of some text file as a single string variable. If applicable, discuss: encoding selection, the possibility of memory-mapping. Of course, in practice one should avoid reading an entire file at once if the file is large and the task can be accomplished incrementally instead (in which case check File IO); this is for those cases where having the entire file is actually what is wanted.	#Ol	Ol	(define content (bytes->string (vec-iter (file->vector "file.txt")))) (print content)
http://rosettacode.org/wiki/Read_entire_file	Read entire file	Task Load the entire contents of some text file as a single string variable. If applicable, discuss: encoding selection, the possibility of memory-mapping. Of course, in practice one should avoid reading an entire file at once if the file is large and the task can be accomplished incrementally instead (in which case check File IO); this is for those cases where having the entire file is actually what is wanted.	#ooRexx	ooRexx	file = 'c:\test.txt' myStream = .stream~new(file) myString = myStream~charIn(,myStream~chars)
http://rosettacode.org/wiki/Regular_expressions	Regular expressions	Task match a string against a regular expression substitute part of a string using a regular expression	#Toka	Toka	#! Include the regex library needs regex #! The two test strings " This is a string" is-data test.1 " Another string" is-data test.2 #! Create a new regex named 'expression' which tries #! to match strings beginning with 'This'. " ^This" regex: expression #! An array to store the results of the match #! (Element 0 = starting offset, Element 1 = ending offset of match) 2 cells is-array match #! Try both test strings against the expression. #! try-regex will return a flag. -1 is TRUE, 0 is FALSE expression test.1 2 match try-regex . expression test.2 2 match try-regex .
http://rosettacode.org/wiki/Regular_expressions	Regular expressions	Task match a string against a regular expression substitute part of a string using a regular expression	#TXR	TXR	@(collect) @(coll :gap 0)@mismatch@{match /dog/}@(end)@suffix @(output) @(rep)@{mismatch}cat@(end)@suffix @(end) @(end)
http://rosettacode.org/wiki/Reverse_a_string	Reverse a string	Task Take a string and reverse it. For example, "asdf" becomes "fdsa". Extra credit Preserve Unicode combining characters. For example, "as⃝df̅" becomes "f̅ds⃝a", not "̅fd⃝sa". Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet	#Elixir	Elixir	IO.puts (String.reverse "asdf") IO.puts (String.reverse "as⃝df̅")
http://rosettacode.org/wiki/Reverse_words_in_a_string	Reverse words in a string	Task Reverse the order of all tokens in each of a number of strings and display the result; the order of characters within a token should not be modified. Example Hey you, Bub! would be shown reversed as: Bub! you, Hey Tokens are any non-space characters separated by spaces (formally, white-space); the visible punctuation form part of the word within which it is located and should not be modified. You may assume that there are no significant non-visible characters in the input. Multiple or superfluous spaces may be compressed into a single space. Some strings have no tokens, so an empty string (or one just containing spaces) would be the result. Display the strings in order (1st, 2nd, 3rd, ···), and one string per line. (You can consider the ten strings as ten lines, and the tokens as words.) Input data (ten lines within the box) line ╔════════════════════════════════════════╗ 1 ║ ---------- Ice and Fire ------------ ║ 2 ║ ║ ◄─── a blank line here. 3 ║ fire, in end will world the say Some ║ 4 ║ ice. in say Some ║ 5 ║ desire of tasted I've what From ║ 6 ║ fire. favor who those with hold I ║ 7 ║ ║ ◄─── a blank line here. 8 ║ ... elided paragraph last ... ║ 9 ║ ║ ◄─── a blank line here. 10 ║ Frost Robert ----------------------- ║ ╚════════════════════════════════════════╝ Cf. Phrase reversals	#Tailspin	Tailspin	def input: ['---------- Ice and Fire ------------', '', 'fire, in end will world the say Some', 'ice. in say Some', 'desire of tasted I''ve what From', 'fire. favor who those with hold I', '', '... elided paragraph last ...', '', 'Frost Robert -----------------------'] ; composer words [ <word>* ] rule word: <~WS> <WS>? end words $input... -> '$ -> words -> $(last..first:-1)...; ' -> !OUT::write
http://rosettacode.org/wiki/Reverse_words_in_a_string	Reverse words in a string	Task Reverse the order of all tokens in each of a number of strings and display the result; the order of characters within a token should not be modified. Example Hey you, Bub! would be shown reversed as: Bub! you, Hey Tokens are any non-space characters separated by spaces (formally, white-space); the visible punctuation form part of the word within which it is located and should not be modified. You may assume that there are no significant non-visible characters in the input. Multiple or superfluous spaces may be compressed into a single space. Some strings have no tokens, so an empty string (or one just containing spaces) would be the result. Display the strings in order (1st, 2nd, 3rd, ···), and one string per line. (You can consider the ten strings as ten lines, and the tokens as words.) Input data (ten lines within the box) line ╔════════════════════════════════════════╗ 1 ║ ---------- Ice and Fire ------------ ║ 2 ║ ║ ◄─── a blank line here. 3 ║ fire, in end will world the say Some ║ 4 ║ ice. in say Some ║ 5 ║ desire of tasted I've what From ║ 6 ║ fire. favor who those with hold I ║ 7 ║ ║ ◄─── a blank line here. 8 ║ ... elided paragraph last ... ║ 9 ║ ║ ◄─── a blank line here. 10 ║ Frost Robert ----------------------- ║ ╚════════════════════════════════════════╝ Cf. Phrase reversals	#Tcl	Tcl	set lines { "---------- Ice and Fire ------------" "" "fire, in end will world the say Some" "ice. in say Some" "desire of tasted I've what From" "fire. favor who those with hold I" "" "... elided paragraph last ..." "" "Frost Robert -----------------------" } foreach line $lines { puts [join [lreverse [regexp -all -inline {\S+} $line]]] # This would also work for data this simple: ### puts [lreverse $line] }
http://rosettacode.org/wiki/Rot-13	Rot-13	Task Implement a rot-13 function (or procedure, class, subroutine, or other "callable" object as appropriate to your programming environment). Optionally wrap this function in a utility program (like tr, which acts like a common UNIX utility, performing a line-by-line rot-13 encoding of every line of input contained in each file listed on its command line, or (if no filenames are passed thereon) acting as a filter on its "standard input." (A number of UNIX scripting languages and utilities, such as awk and sed either default to processing files in this way or have command line switches or modules to easily implement these wrapper semantics, e.g., Perl and Python). The rot-13 encoding is commonly known from the early days of Usenet "Netnews" as a way of obfuscating text to prevent casual reading of spoiler or potentially offensive material. Many news reader and mail user agent programs have built-in rot-13 encoder/decoders or have the ability to feed a message through any external utility script for performing this (or other) actions. The definition of the rot-13 function is to simply replace every letter of the ASCII alphabet with the letter which is "rotated" 13 characters "around" the 26 letter alphabet from its normal cardinal position (wrapping around from z to a as necessary). Thus the letters abc become nop and so on. Technically rot-13 is a "mono-alphabetic substitution cipher" with a trivial "key". A proper implementation should work on upper and lower case letters, preserve case, and pass all non-alphabetic characters in the input stream through without alteration. Related tasks Caesar cipher Substitution Cipher Vigenère Cipher/Cryptanalysis Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet	#X86_Assembly	X86 Assembly	format ELF executable 3 entry start segment readable writeable buf rb 1 segment readable executable start: mov eax, 3 ; syscall "read" mov ebx, 0 ; stdin mov ecx, buf ; buffer for read byte mov edx, 1 ; len (read one byte) int 80h cmp eax, 0 ; EOF? jz exit xor eax, eax ; load read char to eax mov al, [buf] cmp eax, "A" ; see if it is in ascii a-z or A-Z jl print cmp eax, "z" jg print cmp eax, "Z" jle rotup cmp eax, "a" jge rotlow jmp print rotup: sub eax, "A"-13 ; do rot 13 for A-Z cdq mov ebx, 26 div ebx add edx, "A" jmp rotend rotlow: sub eax, "a"-13 ; do rot 13 for a-z cdq mov ebx, 26 div ebx add edx, "a" rotend: mov [buf], dl print: mov eax, 4 ; syscall write mov ebx, 1 ; stdout mov ecx, buf ; *char mov edx, 1 ; string length int 80h jmp start exit: mov eax,1 ; syscall exit xor ebx,ebx ; exit code int 80h
http://rosettacode.org/wiki/Roman_numerals/Encode	Roman numerals/Encode	Task Create a function taking a positive integer as its parameter and returning a string containing the Roman numeral representation of that integer. Modern Roman numerals are written by expressing each digit separately, starting with the left most digit and skipping any digit with a value of zero. In Roman numerals: 1990 is rendered: 1000=M, 900=CM, 90=XC; resulting in MCMXC 2008 is written as 2000=MM, 8=VIII; or MMVIII 1666 uses each Roman symbol in descending order: MDCLXVI	#Wren	Wren	var romans = [ [1000, "M"], [900, "CM"], [500, "D"], [400, "CD"], [100, "C"], [90, "XC"], [50, "L"], [40, "XL"], [10, "X"], [9, "IX"], [5, "V"], [4, "IV"], [1, "I"] ] var encode = Fn.new { \|n\| if (n > 5000 \|\| n < 1) return null var res = "" for (r in romans) { while (n >= r[0]) { n = n - r[0] res = res + r[1] } } return res } System.print(encode.call(1990)) System.print(encode.call(1666)) System.print(encode.call(2008)) System.print(encode.call(2020))
http://rosettacode.org/wiki/Repeat_a_string	Repeat a string	Take a string and repeat it some number of times. Example: repeat("ha", 5) => "hahahahaha" If there is a simpler/more efficient way to repeat a single “character” (i.e. creating a string filled with a certain character), you might want to show that as well (i.e. repeat-char("", 5) => "****"). Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet	#MATLAB_.2F_Octave	MATLAB / Octave	function S = repeat(s , n) S = repmat(s , [1,n]) ; return
http://rosettacode.org/wiki/Repeat_a_string	Repeat a string	Take a string and repeat it some number of times. Example: repeat("ha", 5) => "hahahahaha" If there is a simpler/more efficient way to repeat a single “character” (i.e. creating a string filled with a certain character), you might want to show that as well (i.e. repeat-char("", 5) => "****"). Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet	#Maxima	Maxima	"$"(s, n) := apply(sconcat, makelist(s, n))$ infix("$")$ "abc" $* 5; /* "abcabcabcabcabc" */
http://rosettacode.org/wiki/Remove_duplicate_elements	Remove duplicate elements	Sorting Algorithm This is a sorting algorithm. It may be applied to a set of data in order to sort it. For comparing various sorts, see compare sorts. For other sorting algorithms, see sorting algorithms, or: O(n logn) sorts Heap sort \| Merge sort \| Patience sort \| Quick sort O(n log2n) sorts Shell Sort O(n2) sorts Bubble sort \| Cocktail sort \| Cocktail sort with shifting bounds \| Comb sort \| Cycle sort \| Gnome sort \| Insertion sort \| Selection sort \| Strand sort other sorts Bead sort \| Bogo sort \| Common sorted list \| Composite structures sort \| Custom comparator sort \| Counting sort \| Disjoint sublist sort \| External sort \| Jort sort \| Lexicographical sort \| Natural sorting \| Order by pair comparisons \| Order disjoint list items \| Order two numerical lists \| Object identifier (OID) sort \| Pancake sort \| Quickselect \| Permutation sort \| Radix sort \| Ranking methods \| Remove duplicate elements \| Sleep sort \| Stooge sort \| [Sort letters of a string] \| Three variable sort \| Topological sort \| Tree sort Given an Array, derive a sequence of elements in which all duplicates are removed. There are basically three approaches seen here: Put the elements into a hash table which does not allow duplicates. The complexity is O(n) on average, and O(n2) worst case. This approach requires a hash function for your type (which is compatible with equality), either built-in to your language, or provided by the user. Sort the elements and remove consecutive duplicate elements. The complexity of the best sorting algorithms is O(n log n). This approach requires that your type be "comparable", i.e., have an ordering. Putting the elements into a self-balancing binary search tree is a special case of sorting. Go through the list, and for each element, check the rest of the list to see if it appears again, and discard it if it does. The complexity is O(n2). The up-shot is that this always works on any type (provided that you can test for equality).	#jq	jq	[4,3,2,1,1,2,3,4] \| unique
http://rosettacode.org/wiki/Reduced_row_echelon_form	Reduced row echelon form	Reduced row echelon form You are encouraged to solve this task according to the task description, using any language you may know. Task Show how to compute the reduced row echelon form (a.k.a. row canonical form) of a matrix. The matrix can be stored in any datatype that is convenient (for most languages, this will probably be a two-dimensional array). Built-in functions or this pseudocode (from Wikipedia) may be used: function ToReducedRowEchelonForm(Matrix M) is lead := 0 rowCount := the number of rows in M columnCount := the number of columns in M for 0 ≤ r < rowCount do if columnCount ≤ lead then stop end if i = r while M[i, lead] = 0 do i = i + 1 if rowCount = i then i = r lead = lead + 1 if columnCount = lead then stop end if end if end while Swap rows i and r If M[r, lead] is not 0 divide row r by M[r, lead] for 0 ≤ i < rowCount do if i ≠ r do Subtract M[i, lead] multiplied by row r from row i end if end for lead = lead + 1 end for end function For testing purposes, the RREF of this matrix: 1 2 -1 -4 2 3 -1 -11 -2 0 -3 22 is: 1 0 0 -8 0 1 0 1 0 0 1 -2	#R	R	rref <- function(m) { pivot <- 1 norow <- nrow(m) nocolumn <- ncol(m) for(r in 1:norow) { if ( nocolumn <= pivot ) break; i <- r while( m[i,pivot] == 0 ) { i <- i + 1 if ( norow == i ) { i <- r pivot <- pivot + 1 if ( nocolumn == pivot ) return(m) } } trow <- m[i, ] m[i, ] <- m[r, ] m[r, ] <- trow m[r, ] <- m[r, ] / m[r, pivot] for(i in 1:norow) { if ( i != r ) m[i, ] <- m[i, ] - m[r, ] * m[i, pivot] } pivot <- pivot + 1 } return(m) } m <- matrix(c(1, 2, -1, -4, 2, 3, -1, -11, -2, 0, -3, 22), 3, 4, byrow=TRUE) print(m) print(rref(m))
http://rosettacode.org/wiki/Real_constants_and_functions	Real constants and functions	Task Show how to use the following math constants and functions in your language (if not available, note it): e (base of the natural logarithm) π {\displaystyle \pi } square root logarithm (any base allowed) exponential (ex ) absolute value (a.k.a. "magnitude") floor (largest integer less than or equal to this number--not the same as truncate or int) ceiling (smallest integer not less than this number--not the same as round up) power (xy ) Related task Trigonometric Functions	#Metafont	Metafont	show mexp(256); % outputs e; since MF uses mexp(x) = exp(x/256) show 3.14159; % no pi constant built in; of course we can define it % in several ways... even computing % C/2r (which would be funny since MF handles paths, % and a circle is a path...) show sqrt2; % 1.41422, or in general sqrt(a) show mexp(256x); % see e. show abs(x); % returns \|x\| (the absolute value of the number x, or % the length of the vector x); it is the same as % length(x); plain Metafont in fact says: % let abs = length; show floor(x); % floor show ceiling(x); % ceiling show xy; % * is not a built in: it is defined in the basic macros % set for Metafont (plain Metafont) as a primarydef
http://rosettacode.org/wiki/Real_constants_and_functions	Real constants and functions	Task Show how to use the following math constants and functions in your language (if not available, note it): e (base of the natural logarithm) π {\displaystyle \pi } square root logarithm (any base allowed) exponential (ex ) absolute value (a.k.a. "magnitude") floor (largest integer less than or equal to this number--not the same as truncate or int) ceiling (smallest integer not less than this number--not the same as round up) power (xy ) Related task Trigonometric Functions	#min	min	e ; e pi ; π sqrt ; square root log10 ; common logarithm log2 ; binary logarithm ; no exponential ; no absolute value floor ; greatest whole number smaller than or equal ceil ; smallest whole number greater than or equal trunc ; remove the fractional part (i.e. round towards 0) round ; round number to nth decimal place pow ; power
http://rosettacode.org/wiki/Remove_lines_from_a_file	Remove lines from a file	Task Remove a specific line or a number of lines from a file. This should be implemented as a routine that takes three parameters (filename, starting line, and the number of lines to be removed). For the purpose of this task, line numbers and the number of lines start at one, so to remove the first two lines from the file foobar.txt, the parameters should be: foobar.txt, 1, 2 Empty lines are considered and should still be counted, and if the specified line is empty, it should still be removed. An appropriate message should appear if an attempt is made to remove lines beyond the end of the file.	#zkl	zkl	fcn deleteLinesM(fname, start,num){ blob:=File(fname).read(); // file to memory n:=blob.seek(Void,start-1); // seek to line and remember it blob.del(n,blob.seek(Void,num)-n); File.stdout.write(blob); } deleteLinesM("nn.zkl", 2,5);
http://rosettacode.org/wiki/Read_entire_file	Read entire file	Task Load the entire contents of some text file as a single string variable. If applicable, discuss: encoding selection, the possibility of memory-mapping. Of course, in practice one should avoid reading an entire file at once if the file is large and the task can be accomplished incrementally instead (in which case check File IO); this is for those cases where having the entire file is actually what is wanted.	#Oz	Oz	declare FileHandle = {New Open.file init(name:"test.txt")} FileContents = {FileHandle read(size:all list:$)} in {FileHandle close} {System.printInfo FileContents}
http://rosettacode.org/wiki/Read_entire_file	Read entire file	Task Load the entire contents of some text file as a single string variable. If applicable, discuss: encoding selection, the possibility of memory-mapping. Of course, in practice one should avoid reading an entire file at once if the file is large and the task can be accomplished incrementally instead (in which case check File IO); this is for those cases where having the entire file is actually what is wanted.	#Panda	Panda	file:readme.txt .text
http://rosettacode.org/wiki/Regular_expressions	Regular expressions	Task match a string against a regular expression substitute part of a string using a regular expression	#UNIX_Shell	UNIX Shell	s="I am a string" if [[ $s =~ str..g$ ]]; then echo "the string ends with 'str..g'" fi

http://rosettacode.org/wiki/Reverse_words_in_a_string

Reverse words in a string

Task Reverse the order of all tokens in each of a number of strings and display the result; the order of characters within a token should not be modified. Example Hey you, Bub! would be shown reversed as: Bub! you, Hey Tokens are any non-space characters separated by spaces (formally, white-space); the visible punctuation form part of the word within which it is located and should not be modified. You may assume that there are no significant non-visible characters in the input. Multiple or superfluous spaces may be compressed into a single space. Some strings have no tokens, so an empty string (or one just containing spaces) would be the result. Display the strings in order (1st, 2nd, 3rd, ···), and one string per line. (You can consider the ten strings as ten lines, and the tokens as words.) Input data (ten lines within the box) line ╔════════════════════════════════════════╗ 1 ║ ---------- Ice and Fire ------------ ║ 2 ║ ║ ◄─── a blank line here. 3 ║ fire, in end will world the say Some ║ 4 ║ ice. in say Some ║ 5 ║ desire of tasted I've what From ║ 6 ║ fire. favor who those with hold I ║ 7 ║ ║ ◄─── a blank line here. 8 ║ ... elided paragraph last ... ║ 9 ║ ║ ◄─── a blank line here. 10 ║ Frost Robert ----------------------- ║ ╚════════════════════════════════════════╝ Cf. Phrase reversals

#sed

sed

#!/usr/bin/sed -f G :loop s/^[[:space:]]*$[^[:space:]][^[:space:]]*$$.*\n$/\2 \1/ t loop s/^[[:space:]]*//

http://rosettacode.org/wiki/Rot-13

Rot-13

Task Implement a rot-13 function (or procedure, class, subroutine, or other "callable" object as appropriate to your programming environment). Optionally wrap this function in a utility program (like tr, which acts like a common UNIX utility, performing a line-by-line rot-13 encoding of every line of input contained in each file listed on its command line, or (if no filenames are passed thereon) acting as a filter on its "standard input." (A number of UNIX scripting languages and utilities, such as awk and sed either default to processing files in this way or have command line switches or modules to easily implement these wrapper semantics, e.g., Perl and Python). The rot-13 encoding is commonly known from the early days of Usenet "Netnews" as a way of obfuscating text to prevent casual reading of spoiler or potentially offensive material. Many news reader and mail user agent programs have built-in rot-13 encoder/decoders or have the ability to feed a message through any external utility script for performing this (or other) actions. The definition of the rot-13 function is to simply replace every letter of the ASCII alphabet with the letter which is "rotated" 13 characters "around" the 26 letter alphabet from its normal cardinal position (wrapping around from z to a as necessary). Thus the letters abc become nop and so on. Technically rot-13 is a "mono-alphabetic substitution cipher" with a trivial "key". A proper implementation should work on upper and lower case letters, preserve case, and pass all non-alphabetic characters in the input stream through without alteration. Related tasks Caesar cipher Substitution Cipher Vigenère Cipher/Cryptanalysis Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet

#VBScript

VBScript

option explicit function rot13(a) dim b,n1,n,i b="" for i=1 to len(a) n=asc(mid(a,i,1)) if n>=65 and n<= 91 then n1=(((n-65)+13)mod 26)+65 elseif n>=97 and n<= 123 then n1=(((n-97)+13)mod 26)+97 else n1=n end if b=b & chr(n1) next rot13=b end function const a="The quick brown fox jumps over the lazy dog." dim b,c wscript.echo a b=rot13(a) wscript.echo b c=rot13(b) wscript.echo c

http://rosettacode.org/wiki/Roman_numerals/Encode

Roman numerals/Encode

Task Create a function taking a positive integer as its parameter and returning a string containing the Roman numeral representation of that integer. Modern Roman numerals are written by expressing each digit separately, starting with the left most digit and skipping any digit with a value of zero. In Roman numerals: 1990 is rendered: 1000=M, 900=CM, 90=XC; resulting in MCMXC 2008 is written as 2000=MM, 8=VIII; or MMVIII 1666 uses each Roman symbol in descending order: MDCLXVI

#Ursala

Ursala

#import nat roman = -+ 'IIII'%='IV'+ 'VIIII'%='IX'+ 'XXXX'%='XL'+ 'LXXXX'%='XC'+ 'CCCC'%='CD'+ 'DCCCC'%='CM', ~&plrDlSPSL/'MDCLXVI'+ iota*+ +^|(^|C/~&,\/division)@rlX=>~&iNC <1000,500,100,50,10,5>+-

http://rosettacode.org/wiki/Repeat_a_string

Repeat a string

Take a string and repeat it some number of times. Example: repeat("ha", 5) => "hahahahaha" If there is a simpler/more efficient way to repeat a single “character” (i.e. creating a string filled with a certain character), you might want to show that as well (i.e. repeat-char("*", 5) => "*****"). Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet

#LFE

LFE

(string:copies '"ha" 5)

http://rosettacode.org/wiki/Repeat_a_string

Repeat a string

Take a string and repeat it some number of times. Example: repeat("ha", 5) => "hahahahaha" If there is a simpler/more efficient way to repeat a single “character” (i.e. creating a string filled with a certain character), you might want to show that as well (i.e. repeat-char("*", 5) => "*****"). Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet

#Liberty_BASIC

Liberty BASIC

a$ ="ha " print StringRepeat$( a$, 5) end function StringRepeat$( in$, n) o$ ="" for i =1 to n o$ =o$ +in$ next i StringRepeat$ =o$ end function

http://rosettacode.org/wiki/Return_multiple_values

Return multiple values

Task Show how to return more than one value from a function.

#Ursa

Ursa

def getstrs (int n) decl string<> input while (> n 0) out ": " console append (in string console) input dec n end while return input end getstrs decl int amount out "how many strings do you want to enter? " console set amount (in int console) decl string<> ret set ret (getstrs amount) out endl ret endl console

http://rosettacode.org/wiki/Return_multiple_values

Return multiple values

Task Show how to return more than one value from a function.

#VBA

VBA

Type Contact Name As String firstname As String Age As Byte End Type Function SetContact(N As String, Fn As String, A As Byte) As Contact SetContact.Name = N SetContact.firstname = Fn SetContact.Age = A End Function 'For use : Sub Test_SetContact() Dim Cont As Contact Cont = SetContact("SMITH", "John", 23) Debug.Print Cont.Name & " " & Cont.firstname & ", " & Cont.Age & " years old." End Sub

http://rosettacode.org/wiki/Remove_duplicate_elements

Remove duplicate elements

Sorting Algorithm This is a sorting algorithm. It may be applied to a set of data in order to sort it. For comparing various sorts, see compare sorts. For other sorting algorithms, see sorting algorithms, or: O(n logn) sorts Heap sort | Merge sort | Patience sort | Quick sort O(n log2n) sorts Shell Sort O(n2) sorts Bubble sort | Cocktail sort | Cocktail sort with shifting bounds | Comb sort | Cycle sort | Gnome sort | Insertion sort | Selection sort | Strand sort other sorts Bead sort | Bogo sort | Common sorted list | Composite structures sort | Custom comparator sort | Counting sort | Disjoint sublist sort | External sort | Jort sort | Lexicographical sort | Natural sorting | Order by pair comparisons | Order disjoint list items | Order two numerical lists | Object identifier (OID) sort | Pancake sort | Quickselect | Permutation sort | Radix sort | Ranking methods | Remove duplicate elements | Sleep sort | Stooge sort | [Sort letters of a string] | Three variable sort | Topological sort | Tree sort Given an Array, derive a sequence of elements in which all duplicates are removed. There are basically three approaches seen here: Put the elements into a hash table which does not allow duplicates. The complexity is O(n) on average, and O(n2) worst case. This approach requires a hash function for your type (which is compatible with equality), either built-in to your language, or provided by the user. Sort the elements and remove consecutive duplicate elements. The complexity of the best sorting algorithms is O(n log n). This approach requires that your type be "comparable", i.e., have an ordering. Putting the elements into a self-balancing binary search tree is a special case of sorting. Go through the list, and for each element, check the rest of the list to see if it appears again, and discard it if it does. The complexity is O(n2). The up-shot is that this always works on any type (provided that you can test for equality).

#Inform_7

Inform 7

To decide which list of Ks is (L - list of values of kind K) without duplicates: let result be a list of Ks; repeat with X running through L: add X to result, if absent; decide on result.

http://rosettacode.org/wiki/Reduced_row_echelon_form

Reduced row echelon form

Reduced row echelon form You are encouraged to solve this task according to the task description, using any language you may know. Task Show how to compute the reduced row echelon form (a.k.a. row canonical form) of a matrix. The matrix can be stored in any datatype that is convenient (for most languages, this will probably be a two-dimensional array). Built-in functions or this pseudocode (from Wikipedia) may be used: function ToReducedRowEchelonForm(Matrix M) is lead := 0 rowCount := the number of rows in M columnCount := the number of columns in M for 0 ≤ r < rowCount do if columnCount ≤ lead then stop end if i = r while M[i, lead] = 0 do i = i + 1 if rowCount = i then i = r lead = lead + 1 if columnCount = lead then stop end if end if end while Swap rows i and r If M[r, lead] is not 0 divide row r by M[r, lead] for 0 ≤ i < rowCount do if i ≠ r do Subtract M[i, lead] multiplied by row r from row i end if end for lead = lead + 1 end for end function For testing purposes, the RREF of this matrix: 1 2 -1 -4 2 3 -1 -11 -2 0 -3 22 is: 1 0 0 -8 0 1 0 1 0 0 1 -2

#Perl

Perl

sub rref {our @m; local *m = shift; @m or return; my ($lead, $rows, $cols) = (0, scalar(@m), scalar(@{$m[0]})); foreach my $r (0 .. $rows - 1) {$lead < $cols or return; my $i = $r; until ($m[$i][$lead]) {++$i == $rows or next; $i = $r; ++$lead == $cols and return;} @m[$i, $r] = @m[$r, $i]; my $lv = $m[$r][$lead]; $_ /= $lv foreach @{ $m[$r] }; my @mr = @{ $m[$r] }; foreach my $i (0 .. $rows - 1) {$i == $r and next; ($lv, my $n) = ($m[$i][$lead], -1); $_ -= $lv * $mr[++$n] foreach @{ $m[$i] };} ++$lead;}} sub display { join("\n" => map join(" " => map(sprintf("%4d", $_), @$_)), @{+shift})."\n" } @m = ( [ 1, 2, -1, -4 ], [ 2, 3, -1, -11 ], [ -2, 0, -3, 22 ] ); rref(\@m); print display(\@m);

http://rosettacode.org/wiki/Real_constants_and_functions

Real constants and functions

Task Show how to use the following math constants and functions in your language (if not available, note it): e (base of the natural logarithm) π {\displaystyle \pi } square root logarithm (any base allowed) exponential (ex ) absolute value (a.k.a. "magnitude") floor (largest integer less than or equal to this number--not the same as truncate or int) ceiling (smallest integer not less than this number--not the same as round up) power (xy ) Related task Trigonometric Functions

#Logo

Logo

make "e exp 1 make "pi 2*(RADARCTAN 0 1) sqrt :x ln :x exp :x ; there is no standard abs, floor, or ceiling; only INT and ROUND. power :x :y

http://rosettacode.org/wiki/Real_constants_and_functions

Real constants and functions

Task Show how to use the following math constants and functions in your language (if not available, note it): e (base of the natural logarithm) π {\displaystyle \pi } square root logarithm (any base allowed) exponential (ex ) absolute value (a.k.a. "magnitude") floor (largest integer less than or equal to this number--not the same as truncate or int) ceiling (smallest integer not less than this number--not the same as round up) power (xy ) Related task Trigonometric Functions

#Logtalk

Logtalk

:- object(constants_and_functions). :- public(show/0). show :- write('e = '), E is e, write(E), nl, write('pi = '), PI is pi, write(PI), nl, write('sqrt(2) = '), SQRT is sqrt(2), write(SQRT), nl, % only base e logorithm is avaialable as a standard built-in function write('log(2) = '), LOG is log(2), write(LOG), nl, write('exp(2) = '), EXP is exp(2), write(EXP), nl, write('abs(-1) = '), ABS is abs(-1), write(ABS), nl, write('floor(-3.4) = '), FLOOR is floor(-3.4), write(FLOOR), nl, write('ceiling(-3.4) = '), CEILING is ceiling(-3.4), write(CEILING), nl, write('2 ** -3.4 = '), POWER is 2 ** -3.4, write(POWER), nl. :- end_object.

http://rosettacode.org/wiki/Remove_lines_from_a_file

Remove lines from a file

Task Remove a specific line or a number of lines from a file. This should be implemented as a routine that takes three parameters (filename, starting line, and the number of lines to be removed). For the purpose of this task, line numbers and the number of lines start at one, so to remove the first two lines from the file foobar.txt, the parameters should be: foobar.txt, 1, 2 Empty lines are considered and should still be counted, and if the specified line is empty, it should still be removed. An appropriate message should appear if an attempt is made to remove lines beyond the end of the file.

#Tcl

Tcl

proc removeLines {fileName startLine count} { # Work out range to remove set from [expr {$startLine - 1}] set to [expr {$startLine + $count - 2}] # Read the lines set f [open $fileName] set lines [split [read $f] "\n"] close $f # Write the lines back out, without removed range set f [open $fileName w] puts -nonewline $f [join [lreplace $lines $from $to] "\n"] close $f }

http://rosettacode.org/wiki/Read_entire_file

Read entire file

Task Load the entire contents of some text file as a single string variable. If applicable, discuss: encoding selection, the possibility of memory-mapping. Of course, in practice one should avoid reading an entire file at once if the file is large and the task can be accomplished incrementally instead (in which case check File IO); this is for those cases where having the entire file is actually what is wanted.

#Neko

Neko

/** Read entire file Tectonics: nekoc read-entire-file.neko neko read-entire-file */ var file_contents = $loader.loadprim("std@file_contents", 1); try { var entire_file = file_contents("read-entire-file.neko"); $print("Read: ", $ssize(entire_file), " bytes\n"); } catch e { $print("Exception: ", e, "\n"); }

http://rosettacode.org/wiki/Read_entire_file

Read entire file

Task Load the entire contents of some text file as a single string variable. If applicable, discuss: encoding selection, the possibility of memory-mapping. Of course, in practice one should avoid reading an entire file at once if the file is large and the task can be accomplished incrementally instead (in which case check File IO); this is for those cases where having the entire file is actually what is wanted.

#NetRexx

NetRexx

/* NetRexx */ options replace format comments java crossref symbols nobinary parse arg inFileName . if inFileName = '' | inFileName = '.' then inFileName = './data/dwarfs.json' fileContents = slurp(inFileName) say fileContents return -- Slurp a file and return contents as a Rexx string method slurp(inFileName) public static returns Rexx slurped = Rexx null slurpStr = StringBuilder() ioBuffer = byte[1024] inBytes = int 0 do inFile = File(inFileName) inFileIS = BufferedInputStream(FileInputStream(inFile)) loop label ioLoop until inBytes = -1 slurpStr.append(String(ioBuffer, 0, inBytes)) inBytes = inFileIS.read(ioBuffer) end ioLoop catch exFNF = FileNotFoundException exFNF.printStackTrace catch exIO = IOException exIO.printStackTrace finally do inFileIS.close() catch ex = IOException ex.printStackTrace end end slurped = Rexx(slurpStr.toString) return slurped

http://rosettacode.org/wiki/Rep-string

Rep-string

Given a series of ones and zeroes in a string, define a repeated string or rep-string as a string which is created by repeating a substring of the first N characters of the string truncated on the right to the length of the input string, and in which the substring appears repeated at least twice in the original. For example, the string 10011001100 is a rep-string as the leftmost four characters of 1001 are repeated three times and truncated on the right to give the original string. Note that the requirement for having the repeat occur two or more times means that the repeating unit is never longer than half the length of the input string. Task Write a function/subroutine/method/... that takes a string and returns an indication of if it is a rep-string and the repeated string. (Either the string that is repeated, or the number of repeated characters would suffice). There may be multiple sub-strings that make a string a rep-string - in that case an indication of all, or the longest, or the shortest would suffice. Use the function to indicate the repeating substring if any, in the following: 1001110011 1110111011 0010010010 1010101010 1111111111 0100101101 0100100 101 11 00 1 Show your output on this page. Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet

#Yabasic

Yabasic

data "1001110011", "1110111011", "0010010010", "1010101010", "1111111111", "0100101101", "0100100", "101", "11", "00", "1", "" sub rep$(c$, n) local r$, i for i = 1 to n r$ = r$ + c$ next return r$ end sub do read p$ : if p$ = "" break b$ = "" : l = len(p$) : m = int(l / 2) for i = m to 1 step -1 t$ = left$(p$, i) s$ = rep$(t$, l / i + 1) if p$ = left$(s$, l) b$ = t$ : break next if b$ = "" then print p$, " is not a repeated string" else print p$, " is composed of ", b$, " repeated" end if loop

http://rosettacode.org/wiki/Rep-string

Rep-string

Given a series of ones and zeroes in a string, define a repeated string or rep-string as a string which is created by repeating a substring of the first N characters of the string truncated on the right to the length of the input string, and in which the substring appears repeated at least twice in the original. For example, the string 10011001100 is a rep-string as the leftmost four characters of 1001 are repeated three times and truncated on the right to give the original string. Note that the requirement for having the repeat occur two or more times means that the repeating unit is never longer than half the length of the input string. Task Write a function/subroutine/method/... that takes a string and returns an indication of if it is a rep-string and the repeated string. (Either the string that is repeated, or the number of repeated characters would suffice). There may be multiple sub-strings that make a string a rep-string - in that case an indication of all, or the longest, or the shortest would suffice. Use the function to indicate the repeating substring if any, in the following: 1001110011 1110111011 0010010010 1010101010 1111111111 0100101101 0100100 101 11 00 1 Show your output on this page. Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet

#zkl

zkl

fcn repString(s){ foreach n in ([s.len()/2+1..1,-1]){ Walker.cycle(s[0,n]).pump(s.len(),String) : if(_==s and n*2<=s.len()) return(n); } return(False) }

http://rosettacode.org/wiki/Regular_expressions

Regular expressions

Task match a string against a regular expression substitute part of a string using a regular expression

#Sidef

Sidef

var str = "I am a string"; if (str =~ /string$/) { print "Ends with 'string'\n"; }

http://rosettacode.org/wiki/Regular_expressions

Regular expressions

Task match a string against a regular expression substitute part of a string using a regular expression

#Slate

Slate

'http://slatelanguage.org/test/page?query' =~ '^(([^:/?#]+)\\:)?(//([^/?#]*))?([^?#]*)(\\?([^#]*))?(#(.*))?'. " ==> {'http:'. 'http'. '//slatelanguage.org'. 'slatelanguage.org'. '/test/page'. '?query'. 'query'. Nil} "

http://rosettacode.org/wiki/Reverse_a_string

Reverse a string

Task Take a string and reverse it. For example, "asdf" becomes "fdsa". Extra credit Preserve Unicode combining characters. For example, "as⃝df̅" becomes "f̅ds⃝a", not "̅fd⃝sa". Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet

#EGL

EGL

function reverse( str string ) returns( string ) result string; for ( i int from StrLib.characterLen( str ) to 1 decrement by 1 ) result ::= str[i:i]; end return( result ); end

http://rosettacode.org/wiki/Rename_a_file

Rename a file

Task Rename: a file called input.txt into output.txt and a directory called docs into mydocs. This should be done twice: once "here", i.e. in the current working directory and once in the filesystem root. It can be assumed that the user has the rights to do so. (In unix-type systems, only the user root would have sufficient permissions in the filesystem root.)

#Yorick

Yorick

rename, "input.txt", "output.txt"; rename, "/input.txt", "/output.txt"; rename, "docs", "mydocs"; rename, "/docs", "/mydocs";

http://rosettacode.org/wiki/Rename_a_file

Rename a file

Task Rename: a file called input.txt into output.txt and a directory called docs into mydocs. This should be done twice: once "here", i.e. in the current working directory and once in the filesystem root. It can be assumed that the user has the rights to do so. (In unix-type systems, only the user root would have sufficient permissions in the filesystem root.)

#zkl

zkl

ls -ld input.txt docs output.txt mydocs ls: cannot access 'output.txt': No such file or directory ls: cannot access 'mydocs': No such file or directory drwxr-xr-x 2 craigd craigd 4096 Aug 10 16:24 docs -rw-r--r-- 1 craigd craigd 0 Aug 10 16:24 input.txt $ zkl zkl: File.rename("input.txt","output.txt") True zkl: File.rename("docs","mydocs") True zkl: ^D $ ls -ld input.txt docs output.txt mydocs ls: cannot access 'input.txt': No such file or directory ls: cannot access 'docs': No such file or directory drwxr-xr-x 2 craigd craigd 4096 Aug 10 16:24 mydocs -rw-r--r-- 1 craigd craigd 0 Aug 10 16:24 output.txt

http://rosettacode.org/wiki/Reverse_words_in_a_string

Reverse words in a string

Task Reverse the order of all tokens in each of a number of strings and display the result; the order of characters within a token should not be modified. Example Hey you, Bub! would be shown reversed as: Bub! you, Hey Tokens are any non-space characters separated by spaces (formally, white-space); the visible punctuation form part of the word within which it is located and should not be modified. You may assume that there are no significant non-visible characters in the input. Multiple or superfluous spaces may be compressed into a single space. Some strings have no tokens, so an empty string (or one just containing spaces) would be the result. Display the strings in order (1st, 2nd, 3rd, ···), and one string per line. (You can consider the ten strings as ten lines, and the tokens as words.) Input data (ten lines within the box) line ╔════════════════════════════════════════╗ 1 ║ ---------- Ice and Fire ------------ ║ 2 ║ ║ ◄─── a blank line here. 3 ║ fire, in end will world the say Some ║ 4 ║ ice. in say Some ║ 5 ║ desire of tasted I've what From ║ 6 ║ fire. favor who those with hold I ║ 7 ║ ║ ◄─── a blank line here. 8 ║ ... elided paragraph last ... ║ 9 ║ ║ ◄─── a blank line here. 10 ║ Frost Robert ----------------------- ║ ╚════════════════════════════════════════╝ Cf. Phrase reversals

#Seed7

Seed7

$ include "seed7_05.s7i"; const array string: lines is [] ( "---------- Ice and Fire ------------", "", "fire, in end will world the say Some", "ice. in say Some", "desire of tasted I've what From", "fire. favor who those with hold I", "", "... elided paragraph last ...", "", "Frost Robert -----------------------"); const proc: main is func local var string: line is ""; var array string: words is 0 times ""; var integer: index is 0; begin for line range lines do words := split(line, ' '); for index range length(words) downto 1 do write(words[index] <& " "); end for; writeln; end for; end func;

http://rosettacode.org/wiki/Reverse_words_in_a_string

Reverse words in a string

Task Reverse the order of all tokens in each of a number of strings and display the result; the order of characters within a token should not be modified. Example Hey you, Bub! would be shown reversed as: Bub! you, Hey Tokens are any non-space characters separated by spaces (formally, white-space); the visible punctuation form part of the word within which it is located and should not be modified. You may assume that there are no significant non-visible characters in the input. Multiple or superfluous spaces may be compressed into a single space. Some strings have no tokens, so an empty string (or one just containing spaces) would be the result. Display the strings in order (1st, 2nd, 3rd, ···), and one string per line. (You can consider the ten strings as ten lines, and the tokens as words.) Input data (ten lines within the box) line ╔════════════════════════════════════════╗ 1 ║ ---------- Ice and Fire ------------ ║ 2 ║ ║ ◄─── a blank line here. 3 ║ fire, in end will world the say Some ║ 4 ║ ice. in say Some ║ 5 ║ desire of tasted I've what From ║ 6 ║ fire. favor who those with hold I ║ 7 ║ ║ ◄─── a blank line here. 8 ║ ... elided paragraph last ... ║ 9 ║ ║ ◄─── a blank line here. 10 ║ Frost Robert ----------------------- ║ ╚════════════════════════════════════════╝ Cf. Phrase reversals

#SenseTalk

SenseTalk

set poem to {{ ---------- Ice and Fire ------------ fire, in end will world the say Some ice. in say Some desire of tasted I've what From fire. favor who those with hold I ... elided paragraph last ... Frost Robert ----------------------- }} repeat with each line in poem put (each word of it) reversed joined by space end repeat

http://rosettacode.org/wiki/Rot-13

Rot-13

Task Implement a rot-13 function (or procedure, class, subroutine, or other "callable" object as appropriate to your programming environment). Optionally wrap this function in a utility program (like tr, which acts like a common UNIX utility, performing a line-by-line rot-13 encoding of every line of input contained in each file listed on its command line, or (if no filenames are passed thereon) acting as a filter on its "standard input." (A number of UNIX scripting languages and utilities, such as awk and sed either default to processing files in this way or have command line switches or modules to easily implement these wrapper semantics, e.g., Perl and Python). The rot-13 encoding is commonly known from the early days of Usenet "Netnews" as a way of obfuscating text to prevent casual reading of spoiler or potentially offensive material. Many news reader and mail user agent programs have built-in rot-13 encoder/decoders or have the ability to feed a message through any external utility script for performing this (or other) actions. The definition of the rot-13 function is to simply replace every letter of the ASCII alphabet with the letter which is "rotated" 13 characters "around" the 26 letter alphabet from its normal cardinal position (wrapping around from z to a as necessary). Thus the letters abc become nop and so on. Technically rot-13 is a "mono-alphabetic substitution cipher" with a trivial "key". A proper implementation should work on upper and lower case letters, preserve case, and pass all non-alphabetic characters in the input stream through without alteration. Related tasks Caesar cipher Substitution Cipher Vigenère Cipher/Cryptanalysis Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet

#Wart

Wart

def (rot13 s) (as string (map rot13 (as list s))) Alphabet <- "abcdefghijklmnopqrstuvwxyz" def (rot13 c) :case (and string?.c len.c=1) if ("a" <= c <= "z") let idx (pos c Alphabet) Alphabet (idx+13 % 26) ("A" <= c <= "Z") (downcase.c -> rot13 -> upcase) :else c

http://rosettacode.org/wiki/Roman_numerals/Encode

Roman numerals/Encode

Task Create a function taking a positive integer as its parameter and returning a string containing the Roman numeral representation of that integer. Modern Roman numerals are written by expressing each digit separately, starting with the left most digit and skipping any digit with a value of zero. In Roman numerals: 1990 is rendered: 1000=M, 900=CM, 90=XC; resulting in MCMXC 2008 is written as 2000=MM, 8=VIII; or MMVIII 1666 uses each Roman symbol in descending order: MDCLXVI

#Vala

Vala

string to_roman(int n) requires (n > 0 && n < 5000) { const int[] weights = {1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1}; const string[] symbols = {"M","CM","D","CD","C","XC","L", "XL","X","IX","V","IV","I"}; var roman = "", count = 0; foreach (var w in weights) { while (n >= w) { roman += symbols[count]; n -= w; } if (n == 0) break; count++; } return roman; } void main() { print("%s\n", to_roman(455)); print("%s\n", to_roman(3456)); print("%s\n", to_roman(2488)); }

http://rosettacode.org/wiki/Repeat_a_string

Repeat a string

Take a string and repeat it some number of times. Example: repeat("ha", 5) => "hahahahaha" If there is a simpler/more efficient way to repeat a single “character” (i.e. creating a string filled with a certain character), you might want to show that as well (i.e. repeat-char("*", 5) => "*****"). Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet

#Lingo

Lingo

on rep (str, n) res = "" repeat with i = 1 to n put str after res end repeat return res end

http://rosettacode.org/wiki/Return_multiple_values

Return multiple values

Task Show how to return more than one value from a function.

#Visual_FoxPro

Visual FoxPro

*!* Return multiple values from a function *!* The simplest way is to pass the parameters by reference *!* either by SET UDFPARMS TO REFERENCE, or prefix the variables with @. LOCAL a, b a = 5 b = 6 ? "Sum =", AddUp(@a, @b) && Displays 11 ? "a =", a, "b =", b && Displays 4, 5 ? "Sum =", AddUp(@a, @b) && Displays 9 FUNCTION AddUp(n1, n2) LOCAL n n = n1 + n2 n1 = n1 - 1 n2 = n2 - 1 RETURN n ENDFUNC

http://rosettacode.org/wiki/Return_multiple_values

Return multiple values

Task Show how to return more than one value from a function.

#Wren

Wren

var splitName = Fn.new { |fullName| fullName.split(" ") } var names = splitName.call("George Bernard Shaw") System.print("First name: %(names[0]), middle name: %(names[1]) and surname: %(names[2]).")

http://rosettacode.org/wiki/Remove_duplicate_elements

Remove duplicate elements

Sorting Algorithm This is a sorting algorithm. It may be applied to a set of data in order to sort it. For comparing various sorts, see compare sorts. For other sorting algorithms, see sorting algorithms, or: O(n logn) sorts Heap sort | Merge sort | Patience sort | Quick sort O(n log2n) sorts Shell Sort O(n2) sorts Bubble sort | Cocktail sort | Cocktail sort with shifting bounds | Comb sort | Cycle sort | Gnome sort | Insertion sort | Selection sort | Strand sort other sorts Bead sort | Bogo sort | Common sorted list | Composite structures sort | Custom comparator sort | Counting sort | Disjoint sublist sort | External sort | Jort sort | Lexicographical sort | Natural sorting | Order by pair comparisons | Order disjoint list items | Order two numerical lists | Object identifier (OID) sort | Pancake sort | Quickselect | Permutation sort | Radix sort | Ranking methods | Remove duplicate elements | Sleep sort | Stooge sort | [Sort letters of a string] | Three variable sort | Topological sort | Tree sort Given an Array, derive a sequence of elements in which all duplicates are removed. There are basically three approaches seen here: Put the elements into a hash table which does not allow duplicates. The complexity is O(n) on average, and O(n2) worst case. This approach requires a hash function for your type (which is compatible with equality), either built-in to your language, or provided by the user. Sort the elements and remove consecutive duplicate elements. The complexity of the best sorting algorithms is O(n log n). This approach requires that your type be "comparable", i.e., have an ordering. Putting the elements into a self-balancing binary search tree is a special case of sorting. Go through the list, and for each element, check the rest of the list to see if it appears again, and discard it if it does. The complexity is O(n2). The up-shot is that this always works on any type (provided that you can test for equality).

#IS-BASIC

IS-BASIC

100 PROGRAM "RemoveDu.bas" 110 RANDOMIZE 120 NUMERIC ARR(1 TO 20),TOP 130 LET TOP=FILL(ARR) 140 CALL WRITE(ARR,TOP) 150 LET TOP=REMOVE(ARR) 160 CALL WRITE(ARR,TOP) 170 DEF WRITE(REF A,N) 180 FOR I=1 TO N 190 PRINT A(I); 200 NEXT 210 PRINT 220 END DEF 230 DEF FILL(REF A) 240 LET FILL=UBOUND(A):LET A(LBOUND(A))=1 250 FOR I=LBOUND(A)+1 TO UBOUND(A) 260 LET A(I)=A(I-1)+RND(3) 270 NEXT 280 END DEF 290 DEF REMOVE(REF A) 300 LET ST=0 310 FOR I=LBOUND(A)+1 TO UBOUND(A) 320 IF A(I-1)=A(I) THEN LET ST=ST+1 330 IF ST>0 THEN LET A(I-ST)=A(I) 340 NEXT 350 LET REMOVE=UBOUND(A)-ST 360 END DEF

http://rosettacode.org/wiki/Reduced_row_echelon_form

Reduced row echelon form

Reduced row echelon form You are encouraged to solve this task according to the task description, using any language you may know. Task Show how to compute the reduced row echelon form (a.k.a. row canonical form) of a matrix. The matrix can be stored in any datatype that is convenient (for most languages, this will probably be a two-dimensional array). Built-in functions or this pseudocode (from Wikipedia) may be used: function ToReducedRowEchelonForm(Matrix M) is lead := 0 rowCount := the number of rows in M columnCount := the number of columns in M for 0 ≤ r < rowCount do if columnCount ≤ lead then stop end if i = r while M[i, lead] = 0 do i = i + 1 if rowCount = i then i = r lead = lead + 1 if columnCount = lead then stop end if end if end while Swap rows i and r If M[r, lead] is not 0 divide row r by M[r, lead] for 0 ≤ i < rowCount do if i ≠ r do Subtract M[i, lead] multiplied by row r from row i end if end for lead = lead + 1 end for end function For testing purposes, the RREF of this matrix: 1 2 -1 -4 2 3 -1 -11 -2 0 -3 22 is: 1 0 0 -8 0 1 0 1 0 0 1 -2

#Phix

Phix

with javascript_semantics function ToReducedRowEchelonForm(sequence M) integer lead = 1, rowCount = length(M), columnCount = length(M[1]), i for r=1 to rowCount do if lead>=columnCount then exit end if i = r while M[i][lead]=0 do i += 1 if i=rowCount then i = r lead += 1 if lead=columnCount then exit end if end if end while object mr = sq_div(M[i],M[i][lead]) M[i] = M[r] M[r] = mr for j=1 to rowCount do if j!=r then M[j] = sq_sub(M[j],sq_mul(M[j][lead],M[r])) end if end for lead += 1 end for return M end function ? ToReducedRowEchelonForm( { { 1, 2, -1, -4 }, { 2, 3, -1, -11 }, { -2, 0, -3, 22 } })

http://rosettacode.org/wiki/Real_constants_and_functions

Real constants and functions

Task Show how to use the following math constants and functions in your language (if not available, note it): e (base of the natural logarithm) π {\displaystyle \pi } square root logarithm (any base allowed) exponential (ex ) absolute value (a.k.a. "magnitude") floor (largest integer less than or equal to this number--not the same as truncate or int) ceiling (smallest integer not less than this number--not the same as round up) power (xy ) Related task Trigonometric Functions

#Lua

Lua

math.exp(1) math.pi math.sqrt(x) math.log(x) math.log10(x) math.exp(x) math.abs(x) math.floor(x) math.ceil(x) x^y

http://rosettacode.org/wiki/Real_constants_and_functions

Real constants and functions

Task Show how to use the following math constants and functions in your language (if not available, note it): e (base of the natural logarithm) π {\displaystyle \pi } square root logarithm (any base allowed) exponential (ex ) absolute value (a.k.a. "magnitude") floor (largest integer less than or equal to this number--not the same as truncate or int) ceiling (smallest integer not less than this number--not the same as round up) power (xy ) Related task Trigonometric Functions

#M2000_Interpreter

M2000 Interpreter

Module Checkit { Def exp(x)= 2.71828182845905^x Print Ln(exp(1))==1 Print Log(10^5)==5 Print Sgn(-5)=-1 Print Abs(-2.10#)=2.1# Def exptype$(x)=type$(x) Print exptype$(Abs(-2.1#))="Currency" Print exptype$(Abs(-2.1~))="Single" Print exptype$(Abs(-2.1@))="Decimal" Print exptype$(Abs(-2&))="Long" Print exptype$(Abs(-2%))="Integer" Print exptype$(Abs(-2.212e34))="Double" Print exptype$(Sgn(-2.1#))="Integer" \\ Sgn return integer type Print exptype$(Sgn(-2.212e34))="Integer" \\ Log, Len return double Print exptype$(Log(1000))="Double" Print exptype$(exp(1%))="Double" Print exptype$(Ln(1212%))="Double" \\ power return type Double Print exptype$(2&^2&)="Double" Print exptype$(2&**2&)="Double" Print exptype$(2&*2&)="Long" Print 2**2=4, 2^2=4, 2^2^2=16, 2**2**2=16 \\ floor() and Int() is the same Print Int(-2.7)=-3, Int(2.7)=2 Print Floor(-2.7)=-3, Floor(2.7)=2 Print Ceil(-2.7)=-2, Ceil(2.7)=3 Print round(-2.7, 0)=-3, round(2.7, 0)=3 Print round(-2.2, 0)=-2, round(2.2, 0)=2 Print Sqrt(4)=2 } Checkit

http://rosettacode.org/wiki/Remove_lines_from_a_file

Remove lines from a file

Task Remove a specific line or a number of lines from a file. This should be implemented as a routine that takes three parameters (filename, starting line, and the number of lines to be removed). For the purpose of this task, line numbers and the number of lines start at one, so to remove the first two lines from the file foobar.txt, the parameters should be: foobar.txt, 1, 2 Empty lines are considered and should still be counted, and if the specified line is empty, it should still be removed. An appropriate message should appear if an attempt is made to remove lines beyond the end of the file.

#TUSCRIPT

TUSCRIPT

$$! input=testfile,begnr=3,endnr=4 $$ MODE TUSCRIPT - CREATE inputfile ERROR/STOP CREATE (input,FDF-o,-std-) FILE/ERASE $input LOOP n=1,9 content=CONCAT ("line",n) DATA {content} ENDLOOP ENDFILE - CREATE outputfile output="outputfile" ERROR/STOP CREATE (output,fdf-o,-std-) ACCESS q: READ/RECORDS/utf8 $input L,line ACCESS z: WRITE/RECORDS/utf8 $output L,line PRINT "content: of output-file" LOOP/9999 READ/NEXT/EXIT q IF (begnr<=L&&endnr>=L) CYCLE PRINT line WRITE z ENDLOOP ENDACCESS/PRINT q ENDACCESS/PRINT z

http://rosettacode.org/wiki/Read_entire_file

Read entire file

Task Load the entire contents of some text file as a single string variable. If applicable, discuss: encoding selection, the possibility of memory-mapping. Of course, in practice one should avoid reading an entire file at once if the file is large and the task can be accomplished incrementally instead (in which case check File IO); this is for those cases where having the entire file is actually what is wanted.

#NewLISP

NewLISP

(read-file "filename")

http://rosettacode.org/wiki/Regular_expressions

Regular expressions

Task match a string against a regular expression substitute part of a string using a regular expression

#Smalltalk

Smalltalk

|re s s1| re := Regex fromString: '[a-z]+ing'. s := 'this is a matching string'. s1 := 'this does not match'. (s =~ re) ifMatched: [ :b | b match displayNl ]. (s1 =~ re) ifMatched: [ :b | 'Strangely matched!' displayNl ] ifNotMatched: [ 'no match!' displayNl ]. (s replacingRegex: re with: 'modified') displayNl.

http://rosettacode.org/wiki/Regular_expressions

Regular expressions

Task match a string against a regular expression substitute part of a string using a regular expression

#SNOBOL4

SNOBOL4

label subject pattern = object :(goto)

http://rosettacode.org/wiki/Reverse_a_string

Reverse a string

Task Take a string and reverse it. For example, "asdf" becomes "fdsa". Extra credit Preserve Unicode combining characters. For example, "as⃝df̅" becomes "f̅ds⃝a", not "̅fd⃝sa". Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet

#Eiffel

Eiffel

class APPLICATION create make feature make -- Demonstrate string reversal. do my_string := "Hello World!" my_string.mirror print (my_string) end my_string: STRING -- Used for reversal end

http://rosettacode.org/wiki/Reverse_words_in_a_string

Reverse words in a string

Task Reverse the order of all tokens in each of a number of strings and display the result; the order of characters within a token should not be modified. Example Hey you, Bub! would be shown reversed as: Bub! you, Hey Tokens are any non-space characters separated by spaces (formally, white-space); the visible punctuation form part of the word within which it is located and should not be modified. You may assume that there are no significant non-visible characters in the input. Multiple or superfluous spaces may be compressed into a single space. Some strings have no tokens, so an empty string (or one just containing spaces) would be the result. Display the strings in order (1st, 2nd, 3rd, ···), and one string per line. (You can consider the ten strings as ten lines, and the tokens as words.) Input data (ten lines within the box) line ╔════════════════════════════════════════╗ 1 ║ ---------- Ice and Fire ------------ ║ 2 ║ ║ ◄─── a blank line here. 3 ║ fire, in end will world the say Some ║ 4 ║ ice. in say Some ║ 5 ║ desire of tasted I've what From ║ 6 ║ fire. favor who those with hold I ║ 7 ║ ║ ◄─── a blank line here. 8 ║ ... elided paragraph last ... ║ 9 ║ ║ ◄─── a blank line here. 10 ║ Frost Robert ----------------------- ║ ╚════════════════════════════════════════╝ Cf. Phrase reversals

#Sidef

Sidef

DATA.each{|line| line.words.reverse.join(" ").say}; __DATA__ ---------- Ice and Fire ------------ fire, in end will world the say Some ice. in say Some desire of tasted I've what From fire. favor who those with hold I ... elided paragraph last ... Frost Robert -----------------------

http://rosettacode.org/wiki/Rot-13

Rot-13

Task Implement a rot-13 function (or procedure, class, subroutine, or other "callable" object as appropriate to your programming environment). Optionally wrap this function in a utility program (like tr, which acts like a common UNIX utility, performing a line-by-line rot-13 encoding of every line of input contained in each file listed on its command line, or (if no filenames are passed thereon) acting as a filter on its "standard input." (A number of UNIX scripting languages and utilities, such as awk and sed either default to processing files in this way or have command line switches or modules to easily implement these wrapper semantics, e.g., Perl and Python). The rot-13 encoding is commonly known from the early days of Usenet "Netnews" as a way of obfuscating text to prevent casual reading of spoiler or potentially offensive material. Many news reader and mail user agent programs have built-in rot-13 encoder/decoders or have the ability to feed a message through any external utility script for performing this (or other) actions. The definition of the rot-13 function is to simply replace every letter of the ASCII alphabet with the letter which is "rotated" 13 characters "around" the 26 letter alphabet from its normal cardinal position (wrapping around from z to a as necessary). Thus the letters abc become nop and so on. Technically rot-13 is a "mono-alphabetic substitution cipher" with a trivial "key". A proper implementation should work on upper and lower case letters, preserve case, and pass all non-alphabetic characters in the input stream through without alteration. Related tasks Caesar cipher Substitution Cipher Vigenère Cipher/Cryptanalysis Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet

#Whenever

Whenever

1 2#read()-N(2); 2 2; 3 defer(1 || N(2) > 90 || N(2) < 65) 5#65-N(5); 4 defer(1 || N(2) > 122 || N(2) < 97) 5#97-N(5); 5 5; 6 defer(3 && 4) put(U(((N(2) - N(5) + 13) % 26) + N(5))); 7 defer(1 || N(2) > 64 || N(2) == 0) put(U(N(2))); 8 again(8) defer(6 && 7) 1,-6#N(6)-1,-7#N(7)-1,-3#N(3)-1,-4#N(4)-1; 9 defer(1 || N(2) != 0) -3,-4,-5#N(5),-6,-7,-8; 10 defer(1 || 9) put("\n");

http://rosettacode.org/wiki/Roman_numerals/Encode

Roman numerals/Encode

Task Create a function taking a positive integer as its parameter and returning a string containing the Roman numeral representation of that integer. Modern Roman numerals are written by expressing each digit separately, starting with the left most digit and skipping any digit with a value of zero. In Roman numerals: 1990 is rendered: 1000=M, 900=CM, 90=XC; resulting in MCMXC 2008 is written as 2000=MM, 8=VIII; or MMVIII 1666 uses each Roman symbol in descending order: MDCLXVI

#VBA

VBA

Private Function roman(n As Integer) As String roman = WorksheetFunction.roman(n) End Function Public Sub main() s = [{10, 2016, 800, 2769, 1666, 476, 1453}] For Each x In s Debug.Print roman(CInt(x)); " "; Next x End Sub

http://rosettacode.org/wiki/Repeat_a_string

Repeat a string

Take a string and repeat it some number of times. Example: repeat("ha", 5) => "hahahahaha" If there is a simpler/more efficient way to repeat a single “character” (i.e. creating a string filled with a certain character), you might want to show that as well (i.e. repeat-char("*", 5) => "*****"). Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet

#LiveCode

LiveCode

on mouseUp put repeatString("ha", 5) end mouseUp function repeatString str n repeat n times put str after t end repeat return t end repeatString

http://rosettacode.org/wiki/Repeat_a_string

Repeat a string

Take a string and repeat it some number of times. Example: repeat("ha", 5) => "hahahahaha" If there is a simpler/more efficient way to repeat a single “character” (i.e. creating a string filled with a certain character), you might want to show that as well (i.e. repeat-char("*", 5) => "*****"). Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet

#Logo

Logo

to copies :n :thing [:acc "||] if :n = 0 [output :acc] output (copies :n-1 :thing combine :acc :thing) end

http://rosettacode.org/wiki/Return_multiple_values

Return multiple values

Task Show how to return more than one value from a function.

#XPL0

XPL0

include c:\cxpl\codes; \intrinsic 'code' declarations proc Rect2Polar(X,Y,A,D); \Return two polar coordinate values real X,Y,A,D; [A(0):= ATan2(Y,X); D(0):= Sqrt(X*X+Y*Y); ]; \Rect2Polar real Ang, Dist; [Rect2Polar(4.0, 3.0, @Ang, @Dist); \("@" is a new feature similar to 'addr') RlOut(0, Ang); RlOut(0, Dist); CrLf(0); ]

http://rosettacode.org/wiki/Return_multiple_values

Return multiple values

Task Show how to return more than one value from a function.

#Z80_Assembly

Z80 Assembly

foo: ld hl,&ABCD ld bc,&FFFF ret

http://rosettacode.org/wiki/Remove_duplicate_elements

Remove duplicate elements

Sorting Algorithm This is a sorting algorithm. It may be applied to a set of data in order to sort it. For comparing various sorts, see compare sorts. For other sorting algorithms, see sorting algorithms, or: O(n logn) sorts Heap sort | Merge sort | Patience sort | Quick sort O(n log2n) sorts Shell Sort O(n2) sorts Bubble sort | Cocktail sort | Cocktail sort with shifting bounds | Comb sort | Cycle sort | Gnome sort | Insertion sort | Selection sort | Strand sort other sorts Bead sort | Bogo sort | Common sorted list | Composite structures sort | Custom comparator sort | Counting sort | Disjoint sublist sort | External sort | Jort sort | Lexicographical sort | Natural sorting | Order by pair comparisons | Order disjoint list items | Order two numerical lists | Object identifier (OID) sort | Pancake sort | Quickselect | Permutation sort | Radix sort | Ranking methods | Remove duplicate elements | Sleep sort | Stooge sort | [Sort letters of a string] | Three variable sort | Topological sort | Tree sort Given an Array, derive a sequence of elements in which all duplicates are removed. There are basically three approaches seen here: Put the elements into a hash table which does not allow duplicates. The complexity is O(n) on average, and O(n2) worst case. This approach requires a hash function for your type (which is compatible with equality), either built-in to your language, or provided by the user. Sort the elements and remove consecutive duplicate elements. The complexity of the best sorting algorithms is O(n log n). This approach requires that your type be "comparable", i.e., have an ordering. Putting the elements into a self-balancing binary search tree is a special case of sorting. Go through the list, and for each element, check the rest of the list to see if it appears again, and discard it if it does. The complexity is O(n2). The up-shot is that this always works on any type (provided that you can test for equality).

#J

J

~. 4 3 2 8 0 1 9 5 1 7 6 3 9 9 4 2 1 5 3 2 4 3 2 8 0 1 9 5 7 6 ~. 'chthonic eleemosynary paronomasiac' chtoni elmsyarp

http://rosettacode.org/wiki/Reduced_row_echelon_form

Reduced row echelon form

Reduced row echelon form You are encouraged to solve this task according to the task description, using any language you may know. Task Show how to compute the reduced row echelon form (a.k.a. row canonical form) of a matrix. The matrix can be stored in any datatype that is convenient (for most languages, this will probably be a two-dimensional array). Built-in functions or this pseudocode (from Wikipedia) may be used: function ToReducedRowEchelonForm(Matrix M) is lead := 0 rowCount := the number of rows in M columnCount := the number of columns in M for 0 ≤ r < rowCount do if columnCount ≤ lead then stop end if i = r while M[i, lead] = 0 do i = i + 1 if rowCount = i then i = r lead = lead + 1 if columnCount = lead then stop end if end if end while Swap rows i and r If M[r, lead] is not 0 divide row r by M[r, lead] for 0 ≤ i < rowCount do if i ≠ r do Subtract M[i, lead] multiplied by row r from row i end if end for lead = lead + 1 end for end function For testing purposes, the RREF of this matrix: 1 2 -1 -4 2 3 -1 -11 -2 0 -3 22 is: 1 0 0 -8 0 1 0 1 0 0 1 -2

#PHP

PHP

<?php function rref($matrix) { $lead = 0; $rowCount = count($matrix); if ($rowCount == 0) return $matrix; $columnCount = 0; if (isset($matrix[0])) { $columnCount = count($matrix[0]); } for ($r = 0; $r < $rowCount; $r++) { if ($lead >= $columnCount) break; { $i = $r; while ($matrix[$i][$lead] == 0) { $i++; if ($i == $rowCount) { $i = $r; $lead++; if ($lead == $columnCount) return $matrix; } } $temp = $matrix[$r]; $matrix[$r] = $matrix[$i]; $matrix[$i] = $temp; } { $lv = $matrix[$r][$lead]; for ($j = 0; $j < $columnCount; $j++) { $matrix[$r][$j] = $matrix[$r][$j] / $lv; } } for ($i = 0; $i < $rowCount; $i++) { if ($i != $r) { $lv = $matrix[$i][$lead]; for ($j = 0; $j < $columnCount; $j++) { $matrix[$i][$j] -= $lv * $matrix[$r][$j]; } } } $lead++; } return $matrix; } ?>

http://rosettacode.org/wiki/Real_constants_and_functions

Real constants and functions

Task Show how to use the following math constants and functions in your language (if not available, note it): e (base of the natural logarithm) π {\displaystyle \pi } square root logarithm (any base allowed) exponential (ex ) absolute value (a.k.a. "magnitude") floor (largest integer less than or equal to this number--not the same as truncate or int) ceiling (smallest integer not less than this number--not the same as round up) power (xy ) Related task Trigonometric Functions

#Maple

Maple

> abs(ceil(floor(ln(exp(1)^sqrt(exp(Pi*I)+1))))); 0

http://rosettacode.org/wiki/Remove_lines_from_a_file

Remove lines from a file

Task Remove a specific line or a number of lines from a file. This should be implemented as a routine that takes three parameters (filename, starting line, and the number of lines to be removed). For the purpose of this task, line numbers and the number of lines start at one, so to remove the first two lines from the file foobar.txt, the parameters should be: foobar.txt, 1, 2 Empty lines are considered and should still be counted, and if the specified line is empty, it should still be removed. An appropriate message should appear if an attempt is made to remove lines beyond the end of the file.

#UNIX_Shell

UNIX Shell

#!/bin/sh error() { echo >&2 "$0: $*" exit 1 } [ $# -ne 3 ] && error "Incorrect number of parameters" file=$1 start=$2 count=$3 end=`expr $start + $count - 1` [ -f "$file" ] || error "$file does not exist" sed "$start,${end}d" "$file" >/tmp/$$ && mv /tmp/$$ "$file"

http://rosettacode.org/wiki/Read_entire_file

Read entire file

Task Load the entire contents of some text file as a single string variable. If applicable, discuss: encoding selection, the possibility of memory-mapping. Of course, in practice one should avoid reading an entire file at once if the file is large and the task can be accomplished incrementally instead (in which case check File IO); this is for those cases where having the entire file is actually what is wanted.

#Nim

Nim

readFile(filename)

http://rosettacode.org/wiki/Read_entire_file

Read entire file

Task Load the entire contents of some text file as a single string variable. If applicable, discuss: encoding selection, the possibility of memory-mapping. Of course, in practice one should avoid reading an entire file at once if the file is large and the task can be accomplished incrementally instead (in which case check File IO); this is for those cases where having the entire file is actually what is wanted.

#Objeck

Objeck

string := FileReader->ReadFile("in.txt");

http://rosettacode.org/wiki/Regular_expressions

Regular expressions

Task match a string against a regular expression substitute part of a string using a regular expression

#Standard_ML

Standard ML

CM.make "$/regexp-lib.cm"; structure RE = RegExpFn ( structure P = AwkSyntax structure E = BackTrackEngine); val re = RE.compileString "string$"; val string = "I am a string"; case StringCvt.scanString (RE.find re) string of NONE => print "match failed\n" | SOME match => let val {pos, len} = MatchTree.root match in print ("matched at position " ^ Int.toString pos ^ "\n") end;

http://rosettacode.org/wiki/Regular_expressions

Regular expressions

Task match a string against a regular expression substitute part of a string using a regular expression

#Stata

Stata

scalar s="ars longa vita brevis" * is there a vowel? di regexm(s,"[aeiou]") * replace the first vowel with "?" di regexr(s,"[aeiou]","?")

http://rosettacode.org/wiki/Reverse_a_string

Reverse a string

Task Take a string and reverse it. For example, "asdf" becomes "fdsa". Extra credit Preserve Unicode combining characters. For example, "as⃝df̅" becomes "f̅ds⃝a", not "̅fd⃝sa". Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet

#Ela

Ela

reverse_string str = rev len str where len = length str rev 0 str = "" rev n str = toString (str : nn) +> rev nn str where nn = n - 1 reverse_string "Hello"

http://rosettacode.org/wiki/Reverse_words_in_a_string

Reverse words in a string

Task Reverse the order of all tokens in each of a number of strings and display the result; the order of characters within a token should not be modified. Example Hey you, Bub! would be shown reversed as: Bub! you, Hey Tokens are any non-space characters separated by spaces (formally, white-space); the visible punctuation form part of the word within which it is located and should not be modified. You may assume that there are no significant non-visible characters in the input. Multiple or superfluous spaces may be compressed into a single space. Some strings have no tokens, so an empty string (or one just containing spaces) would be the result. Display the strings in order (1st, 2nd, 3rd, ···), and one string per line. (You can consider the ten strings as ten lines, and the tokens as words.) Input data (ten lines within the box) line ╔════════════════════════════════════════╗ 1 ║ ---------- Ice and Fire ------------ ║ 2 ║ ║ ◄─── a blank line here. 3 ║ fire, in end will world the say Some ║ 4 ║ ice. in say Some ║ 5 ║ desire of tasted I've what From ║ 6 ║ fire. favor who those with hold I ║ 7 ║ ║ ◄─── a blank line here. 8 ║ ... elided paragraph last ... ║ 9 ║ ║ ◄─── a blank line here. 10 ║ Frost Robert ----------------------- ║ ╚════════════════════════════════════════╝ Cf. Phrase reversals

#Smalltalk

Smalltalk

poem := '---------- Ice and Fire ------------ fire, in end will world the say Some ice. in say Some desire of tasted I''ve what From fire. favor who those with hold I ... elided paragraph last ... Frost Robert -----------------------'. (poem lines collect: [ :line | ((line splitOn: ' ') reverse) joinUsing: ' ' ]) joinUsing: (String cr).

http://rosettacode.org/wiki/Reverse_words_in_a_string

Reverse words in a string

Task Reverse the order of all tokens in each of a number of strings and display the result; the order of characters within a token should not be modified. Example Hey you, Bub! would be shown reversed as: Bub! you, Hey Tokens are any non-space characters separated by spaces (formally, white-space); the visible punctuation form part of the word within which it is located and should not be modified. You may assume that there are no significant non-visible characters in the input. Multiple or superfluous spaces may be compressed into a single space. Some strings have no tokens, so an empty string (or one just containing spaces) would be the result. Display the strings in order (1st, 2nd, 3rd, ···), and one string per line. (You can consider the ten strings as ten lines, and the tokens as words.) Input data (ten lines within the box) line ╔════════════════════════════════════════╗ 1 ║ ---------- Ice and Fire ------------ ║ 2 ║ ║ ◄─── a blank line here. 3 ║ fire, in end will world the say Some ║ 4 ║ ice. in say Some ║ 5 ║ desire of tasted I've what From ║ 6 ║ fire. favor who those with hold I ║ 7 ║ ║ ◄─── a blank line here. 8 ║ ... elided paragraph last ... ║ 9 ║ ║ ◄─── a blank line here. 10 ║ Frost Robert ----------------------- ║ ╚════════════════════════════════════════╝ Cf. Phrase reversals

#Sparkling

Sparkling

http://rosettacode.org/wiki/Rot-13

Rot-13

Task Implement a rot-13 function (or procedure, class, subroutine, or other "callable" object as appropriate to your programming environment). Optionally wrap this function in a utility program (like tr, which acts like a common UNIX utility, performing a line-by-line rot-13 encoding of every line of input contained in each file listed on its command line, or (if no filenames are passed thereon) acting as a filter on its "standard input." (A number of UNIX scripting languages and utilities, such as awk and sed either default to processing files in this way or have command line switches or modules to easily implement these wrapper semantics, e.g., Perl and Python). The rot-13 encoding is commonly known from the early days of Usenet "Netnews" as a way of obfuscating text to prevent casual reading of spoiler or potentially offensive material. Many news reader and mail user agent programs have built-in rot-13 encoder/decoders or have the ability to feed a message through any external utility script for performing this (or other) actions. The definition of the rot-13 function is to simply replace every letter of the ASCII alphabet with the letter which is "rotated" 13 characters "around" the 26 letter alphabet from its normal cardinal position (wrapping around from z to a as necessary). Thus the letters abc become nop and so on. Technically rot-13 is a "mono-alphabetic substitution cipher" with a trivial "key". A proper implementation should work on upper and lower case letters, preserve case, and pass all non-alphabetic characters in the input stream through without alteration. Related tasks Caesar cipher Substitution Cipher Vigenère Cipher/Cryptanalysis Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet

#Whitespace

Whitespace

http://rosettacode.org/wiki/Roman_numerals/Encode

Roman numerals/Encode

Task Create a function taking a positive integer as its parameter and returning a string containing the Roman numeral representation of that integer. Modern Roman numerals are written by expressing each digit separately, starting with the left most digit and skipping any digit with a value of zero. In Roman numerals: 1990 is rendered: 1000=M, 900=CM, 90=XC; resulting in MCMXC 2008 is written as 2000=MM, 8=VIII; or MMVIII 1666 uses each Roman symbol in descending order: MDCLXVI

#Vedit_macro_language

Vedit macro language

// Main program for testing the function // do { #1 = Get_Num("Number to convert: ", STATLINE) Call("NUM_TO_ROMAN") Num_Type(#1, NOCR) Message(" = ") Reg_Type(1) Type_Newline } while (Reg_Size(1)) Return // Convert numeric value into Roman number // #1 = number to convert; on return: T-reg(1) = Roman number // :NUM_TO_ROMAN: Reg_Empty(1) // @1 = Results (Roman number) if (#1 < 1) { Return } // non-positive numbers return empty string Buf_Switch(Buf_Free) Ins_Text("M1000,CM900,D500,CD400,C100,XC90,L50,XL40,X10,IX9,V5,IV4,I1") BOF #2 = #1 Repeat(ALL) { Search("|A|[|A]", ADVANCE+ERRBREAK) // get next item from conversion list Reg_Copy_Block(20, CP-Chars_Matched, CP) // @20 = Letter(s) to be inserted #11 = Num_Eval() // #11 = magnitude (1000...1) while (#2 >= #11) { Reg_Set(1, @20, APPEND) #2 -= #11 } } Buf_Quit(OK) Return

http://rosettacode.org/wiki/Repeat_a_string

Repeat a string

Take a string and repeat it some number of times. Example: repeat("ha", 5) => "hahahahaha" If there is a simpler/more efficient way to repeat a single “character” (i.e. creating a string filled with a certain character), you might want to show that as well (i.e. repeat-char("*", 5) => "*****"). Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet

#Lua

Lua

function repeats(s, n) return n > 0 and s .. repeats(s, n-1) or "" end

http://rosettacode.org/wiki/Return_multiple_values

Return multiple values

Task Show how to return more than one value from a function.

#zkl

zkl

fcn f{return(1,2,"three")} a,b,c:=f() // a==1, b==2, c=="three"

http://rosettacode.org/wiki/Remove_duplicate_elements

Remove duplicate elements

Sorting Algorithm This is a sorting algorithm. It may be applied to a set of data in order to sort it. For comparing various sorts, see compare sorts. For other sorting algorithms, see sorting algorithms, or: O(n logn) sorts Heap sort | Merge sort | Patience sort | Quick sort O(n log2n) sorts Shell Sort O(n2) sorts Bubble sort | Cocktail sort | Cocktail sort with shifting bounds | Comb sort | Cycle sort | Gnome sort | Insertion sort | Selection sort | Strand sort other sorts Bead sort | Bogo sort | Common sorted list | Composite structures sort | Custom comparator sort | Counting sort | Disjoint sublist sort | External sort | Jort sort | Lexicographical sort | Natural sorting | Order by pair comparisons | Order disjoint list items | Order two numerical lists | Object identifier (OID) sort | Pancake sort | Quickselect | Permutation sort | Radix sort | Ranking methods | Remove duplicate elements | Sleep sort | Stooge sort | [Sort letters of a string] | Three variable sort | Topological sort | Tree sort Given an Array, derive a sequence of elements in which all duplicates are removed. There are basically three approaches seen here: Put the elements into a hash table which does not allow duplicates. The complexity is O(n) on average, and O(n2) worst case. This approach requires a hash function for your type (which is compatible with equality), either built-in to your language, or provided by the user. Sort the elements and remove consecutive duplicate elements. The complexity of the best sorting algorithms is O(n log n). This approach requires that your type be "comparable", i.e., have an ordering. Putting the elements into a self-balancing binary search tree is a special case of sorting. Go through the list, and for each element, check the rest of the list to see if it appears again, and discard it if it does. The complexity is O(n2). The up-shot is that this always works on any type (provided that you can test for equality).

#Java

Java

import java.util.*; class Test { public static void main(String[] args) { Object[] data = {1, 1, 2, 2, 3, 3, 3, "a", "a", "b", "b", "c", "d"}; Set<Object> uniqueSet = new HashSet<Object>(Arrays.asList(data)); for (Object o : uniqueSet) System.out.printf("%s ", o); } }

http://rosettacode.org/wiki/Reduced_row_echelon_form

Reduced row echelon form

Reduced row echelon form You are encouraged to solve this task according to the task description, using any language you may know. Task Show how to compute the reduced row echelon form (a.k.a. row canonical form) of a matrix. The matrix can be stored in any datatype that is convenient (for most languages, this will probably be a two-dimensional array). Built-in functions or this pseudocode (from Wikipedia) may be used: function ToReducedRowEchelonForm(Matrix M) is lead := 0 rowCount := the number of rows in M columnCount := the number of columns in M for 0 ≤ r < rowCount do if columnCount ≤ lead then stop end if i = r while M[i, lead] = 0 do i = i + 1 if rowCount = i then i = r lead = lead + 1 if columnCount = lead then stop end if end if end while Swap rows i and r If M[r, lead] is not 0 divide row r by M[r, lead] for 0 ≤ i < rowCount do if i ≠ r do Subtract M[i, lead] multiplied by row r from row i end if end for lead = lead + 1 end for end function For testing purposes, the RREF of this matrix: 1 2 -1 -4 2 3 -1 -11 -2 0 -3 22 is: 1 0 0 -8 0 1 0 1 0 0 1 -2

#PicoLisp

PicoLisp

(de reducedRowEchelonForm (Mat) (let (Lead 1 Cols (length (car Mat))) (for (X Mat X (cdr X)) (NIL (loop (T (seek '((R) (n0 (get R 1 Lead))) X) @ ) (T (> (inc 'Lead) Cols)) ) ) (xchg @ X) (let D (get X 1 Lead) (map '((R) (set R (/ (car R) D))) (car X) ) ) (for Y Mat (unless (== Y (car X)) (let N (- (get Y Lead)) (map '((Dst Src) (inc Dst (* N (car Src))) ) Y (car X) ) ) ) ) (T (> (inc 'Lead) Cols)) ) ) Mat )

http://rosettacode.org/wiki/Real_constants_and_functions

Real constants and functions

Task Show how to use the following math constants and functions in your language (if not available, note it): e (base of the natural logarithm) π {\displaystyle \pi } square root logarithm (any base allowed) exponential (ex ) absolute value (a.k.a. "magnitude") floor (largest integer less than or equal to this number--not the same as truncate or int) ceiling (smallest integer not less than this number--not the same as round up) power (xy ) Related task Trigonometric Functions

#Mathematica.2FWolfram_Language

Mathematica/Wolfram Language

E Pi Sqrt[x] Log[x] Log[b,x] Exp[x] Abs[x] Floor[x] Ceiling[x] Power[x, y]

http://rosettacode.org/wiki/Real_constants_and_functions

Real constants and functions

Task Show how to use the following math constants and functions in your language (if not available, note it): e (base of the natural logarithm) π {\displaystyle \pi } square root logarithm (any base allowed) exponential (ex ) absolute value (a.k.a. "magnitude") floor (largest integer less than or equal to this number--not the same as truncate or int) ceiling (smallest integer not less than this number--not the same as round up) power (xy ) Related task Trigonometric Functions

#MATLAB_.2F_Octave

MATLAB / Octave

exp(1) % e pi % pi sqrt(x) % square root log(x) % natural logarithm log2(x) % logarithm base 2 log10(x) % logarithm base 10 exp(x) % exponential abs(-x) % absolute value floor(x) % floor ceil(x) % ceiling x^y % power

http://rosettacode.org/wiki/Remove_lines_from_a_file

Remove lines from a file

Task Remove a specific line or a number of lines from a file. This should be implemented as a routine that takes three parameters (filename, starting line, and the number of lines to be removed). For the purpose of this task, line numbers and the number of lines start at one, so to remove the first two lines from the file foobar.txt, the parameters should be: foobar.txt, 1, 2 Empty lines are considered and should still be counted, and if the specified line is empty, it should still be removed. An appropriate message should appear if an attempt is made to remove lines beyond the end of the file.

#VBA

VBA

Option Explicit Sub Main() 'See Output #1 RemoveLines "C:\Users\" & Environ("username") & "\Desktop\foobar.txt", 11, 5 'See Output #2 RemoveLines "C:\Users\" & Environ("username") & "\Desktop\foobar.txt", 8, 5 'See Output #3 RemoveLines "C:\Users\" & Environ("username") & "\Desktop\foobar.txt", 3, 5 End Sub Private Sub RemoveLines(StrFile As String, StartLine As Long, NumberOfLines As Long) Dim Nb As Integer, s As String, count As Long, out As String Nb = FreeFile Open StrFile For Input As #Nb While Not EOF(Nb) count = count + 1 Line Input #Nb, s If count < StartLine Or count >= StartLine + NumberOfLines Then out = out & s & vbCrLf End If Wend Close #Nb If StartLine >= count Then MsgBox "The file contains only " & count & " lines" ElseIf StartLine + NumberOfLines > count Then MsgBox "You only can remove " & count - StartLine & " lines" Else Nb = FreeFile Open StrFile For Output As #Nb Print #Nb, out Close #Nb End If End Sub

http://rosettacode.org/wiki/Read_entire_file

Read entire file

Task Load the entire contents of some text file as a single string variable. If applicable, discuss: encoding selection, the possibility of memory-mapping. Of course, in practice one should avoid reading an entire file at once if the file is large and the task can be accomplished incrementally instead (in which case check File IO); this is for those cases where having the entire file is actually what is wanted.

#Objective-C

Objective-C

/*** 0. PREPARATION */ // We need a text file to read; let's redirect a C string to a new file // using the shell by way of the stdlib system() function. system ("echo \"Hello, World!\" > ~/HelloRosetta"); /*** 1. THE TASK */ // Instantiate an NSString which describes the filesystem location of // the file we will be reading. NSString *filePath = [NSHomeDirectory() stringByAppendingPathComponent:@"HelloRosetta"]; // The selector we're going to use to complete this task, // stringWithContentsOfFile:encoding:error, has an optional `error' // parameter which can be used to return information about any // errors it might run into. It's optional, but we'll create an NSError // anyways to demonstrate best practice. NSError *anError; // And finally, the task: read and store the contents of a file as an // NSString. NSString *aString = [NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:&anError]; // If the file read was unsuccessful, display the error description. // Otherwise, display the NSString. if (!aString) { NSLog(@"%@", [anError localizedDescription]); } else { NSLog(@"%@", aString); }

http://rosettacode.org/wiki/Read_entire_file

Read entire file

Task Load the entire contents of some text file as a single string variable. If applicable, discuss: encoding selection, the possibility of memory-mapping. Of course, in practice one should avoid reading an entire file at once if the file is large and the task can be accomplished incrementally instead (in which case check File IO); this is for those cases where having the entire file is actually what is wanted.

#OCaml

OCaml

let load_file f = let ic = open_in f in let n = in_channel_length ic in let s = Bytes.create n in really_input ic s 0 n; close_in ic; (s)

http://rosettacode.org/wiki/Regular_expressions

Regular expressions

Task match a string against a regular expression substitute part of a string using a regular expression

#Swift

Swift

import Foundation let str = "I am a string" if let range = str.rangeOfString("string$", options: .RegularExpressionSearch) { println("Ends with 'string'") }

http://rosettacode.org/wiki/Regular_expressions

Regular expressions

Task match a string against a regular expression substitute part of a string using a regular expression

#Tcl

Tcl

set theString "I am a string" if {[regexp -- {string$} $theString]} { puts "Ends with 'string'" } if {![regexp -- {^You} $theString]} { puts "Does not start with 'You'" }

http://rosettacode.org/wiki/Reverse_a_string

Reverse a string

Task Take a string and reverse it. For example, "asdf" becomes "fdsa". Extra credit Preserve Unicode combining characters. For example, "as⃝df̅" becomes "f̅ds⃝a", not "̅fd⃝sa". Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet

#Elena

Elena

import system'routines; import extensions; import extensions'text; extension extension { reversedLiteral() = self.toArray().sequenceReverse().summarize(new StringWriter()); } public program() { console.printLine("Hello World".reversedLiteral()) }

http://rosettacode.org/wiki/Reverse_words_in_a_string

Reverse words in a string

Task Reverse the order of all tokens in each of a number of strings and display the result; the order of characters within a token should not be modified. Example Hey you, Bub! would be shown reversed as: Bub! you, Hey Tokens are any non-space characters separated by spaces (formally, white-space); the visible punctuation form part of the word within which it is located and should not be modified. You may assume that there are no significant non-visible characters in the input. Multiple or superfluous spaces may be compressed into a single space. Some strings have no tokens, so an empty string (or one just containing spaces) would be the result. Display the strings in order (1st, 2nd, 3rd, ···), and one string per line. (You can consider the ten strings as ten lines, and the tokens as words.) Input data (ten lines within the box) line ╔════════════════════════════════════════╗ 1 ║ ---------- Ice and Fire ------------ ║ 2 ║ ║ ◄─── a blank line here. 3 ║ fire, in end will world the say Some ║ 4 ║ ice. in say Some ║ 5 ║ desire of tasted I've what From ║ 6 ║ fire. favor who those with hold I ║ 7 ║ ║ ◄─── a blank line here. 8 ║ ... elided paragraph last ... ║ 9 ║ ║ ◄─── a blank line here. 10 ║ Frost Robert ----------------------- ║ ╚════════════════════════════════════════╝ Cf. Phrase reversals

#Standard_ML

Standard ML

val lines = [ " ---------- Ice and Fire ------------ ", " ", " fire, in end will world the say Some ", " ice. in say Some ", " desire of tasted I've what From ", " fire. favor who those with hold I ", " ", " ... elided paragraph last ... ", " ", " Frost Robert ----------------------- " ] val revWords = String.concatWith " " o rev o String.tokens Char.isSpace val () = app (fn line => print (revWords line ^ "\n")) lines

http://rosettacode.org/wiki/Reverse_words_in_a_string

Reverse words in a string

Task Reverse the order of all tokens in each of a number of strings and display the result; the order of characters within a token should not be modified. Example Hey you, Bub! would be shown reversed as: Bub! you, Hey Tokens are any non-space characters separated by spaces (formally, white-space); the visible punctuation form part of the word within which it is located and should not be modified. You may assume that there are no significant non-visible characters in the input. Multiple or superfluous spaces may be compressed into a single space. Some strings have no tokens, so an empty string (or one just containing spaces) would be the result. Display the strings in order (1st, 2nd, 3rd, ···), and one string per line. (You can consider the ten strings as ten lines, and the tokens as words.) Input data (ten lines within the box) line ╔════════════════════════════════════════╗ 1 ║ ---------- Ice and Fire ------------ ║ 2 ║ ║ ◄─── a blank line here. 3 ║ fire, in end will world the say Some ║ 4 ║ ice. in say Some ║ 5 ║ desire of tasted I've what From ║ 6 ║ fire. favor who those with hold I ║ 7 ║ ║ ◄─── a blank line here. 8 ║ ... elided paragraph last ... ║ 9 ║ ║ ◄─── a blank line here. 10 ║ Frost Robert ----------------------- ║ ╚════════════════════════════════════════╝ Cf. Phrase reversals

#Swift

Swift

import Foundation // convenience extension for better clarity extension String { var lines: [String] { get { return self.componentsSeparatedByCharactersInSet(NSCharacterSet.newlineCharacterSet()) } } var words: [String] { get { return self.componentsSeparatedByCharactersInSet(NSCharacterSet.whitespaceCharacterSet()) } } } let input = "---------- Ice and Fire ------------\n\nfire, in end will world the say Some\nice. in say Some\ndesire of tasted I've what From\nfire. favor who those with hold I\n\n... elided paragraph last ...\n\nFrost Robert -----------------------\n" let output = input.lines.map { $0.words.reverse().joinWithSeparator(" ") }.joinWithSeparator("\n") print(output)

http://rosettacode.org/wiki/Rot-13

Rot-13

Task Implement a rot-13 function (or procedure, class, subroutine, or other "callable" object as appropriate to your programming environment). Optionally wrap this function in a utility program (like tr, which acts like a common UNIX utility, performing a line-by-line rot-13 encoding of every line of input contained in each file listed on its command line, or (if no filenames are passed thereon) acting as a filter on its "standard input." (A number of UNIX scripting languages and utilities, such as awk and sed either default to processing files in this way or have command line switches or modules to easily implement these wrapper semantics, e.g., Perl and Python). The rot-13 encoding is commonly known from the early days of Usenet "Netnews" as a way of obfuscating text to prevent casual reading of spoiler or potentially offensive material. Many news reader and mail user agent programs have built-in rot-13 encoder/decoders or have the ability to feed a message through any external utility script for performing this (or other) actions. The definition of the rot-13 function is to simply replace every letter of the ASCII alphabet with the letter which is "rotated" 13 characters "around" the 26 letter alphabet from its normal cardinal position (wrapping around from z to a as necessary). Thus the letters abc become nop and so on. Technically rot-13 is a "mono-alphabetic substitution cipher" with a trivial "key". A proper implementation should work on upper and lower case letters, preserve case, and pass all non-alphabetic characters in the input stream through without alteration. Related tasks Caesar cipher Substitution Cipher Vigenère Cipher/Cryptanalysis Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet

#Wren

Wren

var rot13 = Fn.new { |s| var bytes = s.bytes.toList for (i in 0...bytes.count) { var c = bytes[i] if ((c >= 65 && c <= 77) || (c >= 97 && c <= 109)) { bytes[i] = c + 13 } else if ((c >= 78 && c <= 90) || (c >= 110 && c <= 122)) { bytes[i] = c - 13 } } return bytes.map { |b| String.fromByte(b) }.join() } System.print(rot13.call("nowhere ABJURER"))

http://rosettacode.org/wiki/Roman_numerals/Encode

Roman numerals/Encode

Task Create a function taking a positive integer as its parameter and returning a string containing the Roman numeral representation of that integer. Modern Roman numerals are written by expressing each digit separately, starting with the left most digit and skipping any digit with a value of zero. In Roman numerals: 1990 is rendered: 1000=M, 900=CM, 90=XC; resulting in MCMXC 2008 is written as 2000=MM, 8=VIII; or MMVIII 1666 uses each Roman symbol in descending order: MDCLXVI

#Visual_Basic

Visual Basic

Function toRoman(value) As String Dim arabic As Variant Dim roman As Variant arabic = Array(1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1) roman = Array("M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I") Dim i As Integer, result As String For i = 0 To 12 Do While value >= arabic(i) result = result + roman(i) value = value - arabic(i) Loop Next i toRoman = result End Function Sub Main() MsgBox toRoman(Val(InputBox("Number, please"))) End Sub

http://rosettacode.org/wiki/Repeat_a_string

Repeat a string

Take a string and repeat it some number of times. Example: repeat("ha", 5) => "hahahahaha" If there is a simpler/more efficient way to repeat a single “character” (i.e. creating a string filled with a certain character), you might want to show that as well (i.e. repeat-char("*", 5) => "*****"). Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet

#Maple

Maple

> use StringTools in > Repeat( "abc", 10 ); # repeat an arbitrary string > Fill( "x", 20 ) # repeat a character > end use; "abcabcabcabcabcabcabcabcabcabc" "xxxxxxxxxxxxxxxxxxxx"

http://rosettacode.org/wiki/Repeat_a_string

Repeat a string

Take a string and repeat it some number of times. Example: repeat("ha", 5) => "hahahahaha" If there is a simpler/more efficient way to repeat a single “character” (i.e. creating a string filled with a certain character), you might want to show that as well (i.e. repeat-char("*", 5) => "*****"). Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet

#Mathematica.2FWolfram_Language

Mathematica/Wolfram Language

(* solution 1 *) rep[n_Integer,s_String]:=Apply[StringJoin,ConstantArray[s,{n}]] (* solution 2 -- @@ is the infix form of Apply[] *) rep[n_Integer,s_String]:=StringJoin@@Table[s,{n}] (* solution 3 -- demonstrating another of the large number of looping constructs available *) rep[n_Integer,s_String]:=Nest[StringJoin[s, #] &,s,n-1]

http://rosettacode.org/wiki/Remove_duplicate_elements

Remove duplicate elements

Sorting Algorithm This is a sorting algorithm. It may be applied to a set of data in order to sort it. For comparing various sorts, see compare sorts. For other sorting algorithms, see sorting algorithms, or: O(n logn) sorts Heap sort | Merge sort | Patience sort | Quick sort O(n log2n) sorts Shell Sort O(n2) sorts Bubble sort | Cocktail sort | Cocktail sort with shifting bounds | Comb sort | Cycle sort | Gnome sort | Insertion sort | Selection sort | Strand sort other sorts Bead sort | Bogo sort | Common sorted list | Composite structures sort | Custom comparator sort | Counting sort | Disjoint sublist sort | External sort | Jort sort | Lexicographical sort | Natural sorting | Order by pair comparisons | Order disjoint list items | Order two numerical lists | Object identifier (OID) sort | Pancake sort | Quickselect | Permutation sort | Radix sort | Ranking methods | Remove duplicate elements | Sleep sort | Stooge sort | [Sort letters of a string] | Three variable sort | Topological sort | Tree sort Given an Array, derive a sequence of elements in which all duplicates are removed. There are basically three approaches seen here: Put the elements into a hash table which does not allow duplicates. The complexity is O(n) on average, and O(n2) worst case. This approach requires a hash function for your type (which is compatible with equality), either built-in to your language, or provided by the user. Sort the elements and remove consecutive duplicate elements. The complexity of the best sorting algorithms is O(n log n). This approach requires that your type be "comparable", i.e., have an ordering. Putting the elements into a self-balancing binary search tree is a special case of sorting. Go through the list, and for each element, check the rest of the list to see if it appears again, and discard it if it does. The complexity is O(n2). The up-shot is that this always works on any type (provided that you can test for equality).

#JavaScript

JavaScript

function unique(ary) { // concat() with no args is a way to clone an array var u = ary.concat().sort(); for (var i = 1; i < u.length; ) { if (u[i-1] === u[i]) u.splice(i,1); else i++; } return u; } var ary = [1, 2, 3, "a", "b", "c", 2, 3, 4, "b", "c", "d", "4"]; var uniq = unique(ary); for (var i = 0; i < uniq.length; i++) print(uniq[i] + "\t" + typeof(uniq[i]));

http://rosettacode.org/wiki/Reduced_row_echelon_form

Reduced row echelon form

Reduced row echelon form You are encouraged to solve this task according to the task description, using any language you may know. Task Show how to compute the reduced row echelon form (a.k.a. row canonical form) of a matrix. The matrix can be stored in any datatype that is convenient (for most languages, this will probably be a two-dimensional array). Built-in functions or this pseudocode (from Wikipedia) may be used: function ToReducedRowEchelonForm(Matrix M) is lead := 0 rowCount := the number of rows in M columnCount := the number of columns in M for 0 ≤ r < rowCount do if columnCount ≤ lead then stop end if i = r while M[i, lead] = 0 do i = i + 1 if rowCount = i then i = r lead = lead + 1 if columnCount = lead then stop end if end if end while Swap rows i and r If M[r, lead] is not 0 divide row r by M[r, lead] for 0 ≤ i < rowCount do if i ≠ r do Subtract M[i, lead] multiplied by row r from row i end if end for lead = lead + 1 end for end function For testing purposes, the RREF of this matrix: 1 2 -1 -4 2 3 -1 -11 -2 0 -3 22 is: 1 0 0 -8 0 1 0 1 0 0 1 -2

#Python

Python

def ToReducedRowEchelonForm( M): if not M: return lead = 0 rowCount = len(M) columnCount = len(M[0]) for r in range(rowCount): if lead >= columnCount: return i = r while M[i][lead] == 0: i += 1 if i == rowCount: i = r lead += 1 if columnCount == lead: return M[i],M[r] = M[r],M[i] lv = M[r][lead] M[r] = [ mrx / float(lv) for mrx in M[r]] for i in range(rowCount): if i != r: lv = M[i][lead] M[i] = [ iv - lv*rv for rv,iv in zip(M[r],M[i])] lead += 1 mtx = [ [ 1, 2, -1, -4], [ 2, 3, -1, -11], [-2, 0, -3, 22],] ToReducedRowEchelonForm( mtx ) for rw in mtx: print ', '.join( (str(rv) for rv in rw) )

http://rosettacode.org/wiki/Real_constants_and_functions

Real constants and functions

Task Show how to use the following math constants and functions in your language (if not available, note it): e (base of the natural logarithm) π {\displaystyle \pi } square root logarithm (any base allowed) exponential (ex ) absolute value (a.k.a. "magnitude") floor (largest integer less than or equal to this number--not the same as truncate or int) ceiling (smallest integer not less than this number--not the same as round up) power (xy ) Related task Trigonometric Functions

#MAXScript

MAXScript

e -- Euler's number pi -- pi log x -- natural logarithm log10 x -- log base 10 exp x -- exponantial abs x -- absolute value floor x -- floor ceil x -- ceiling pow x y -- power

http://rosettacode.org/wiki/Real_constants_and_functions

Real constants and functions

Task Show how to use the following math constants and functions in your language (if not available, note it): e (base of the natural logarithm) π {\displaystyle \pi } square root logarithm (any base allowed) exponential (ex ) absolute value (a.k.a. "magnitude") floor (largest integer less than or equal to this number--not the same as truncate or int) ceiling (smallest integer not less than this number--not the same as round up) power (xy ) Related task Trigonometric Functions

#Mercury

Mercury

math.pi % Pi. math.e % Euler's number. math.sqrt(X) % Square root of X. math.ln(X) % Natural logarithm of X. math.log10(X) % Logarithm to the base 10 of X. math.log2(X) % Logarithm to the base 2 of X. math.log(B, X) % Logarithm to the base B of X. math.exp(X) % e raised to the power of X. float.abs(X) % Absolute value of X. math.floor(X) % Floor of X. math.ceiling(X) % Ceiling of X. math.pow(X, Y) % X raised to the power of Y.

http://rosettacode.org/wiki/Remove_lines_from_a_file

Remove lines from a file

Task Remove a specific line or a number of lines from a file. This should be implemented as a routine that takes three parameters (filename, starting line, and the number of lines to be removed). For the purpose of this task, line numbers and the number of lines start at one, so to remove the first two lines from the file foobar.txt, the parameters should be: foobar.txt, 1, 2 Empty lines are considered and should still be counted, and if the specified line is empty, it should still be removed. An appropriate message should appear if an attempt is made to remove lines beyond the end of the file.

#VBScript

VBScript

Sub remove_lines(filepath,start,number) Set objFSO = CreateObject("Scripting.FileSystemObject") Set InFile = objFSO.OpenTextFile(filepath,1,False) line_count = 1 discard_count = 1 out_txt = "" Do Until InFile.AtEndOfStream line = InFile.ReadLine If line_count <> start Then If InFile.AtEndOfStream = False Then out_txt = out_txt & line & vbCrLf Else out_txt = out_txt & line End If line_count = line_count + 1 Else Do Until discard_count = number InFile.SkipLine discard_count = discard_count + 1 Loop line_count = line_count + 1 End If Loop InFile.Close Set OutFile = objFSO.OpenTextFile(filepath,2,False) OutFile.Write(out_txt) OutFile.Close Set objFSO = Nothing End Sub Call remove_lines("C:\Test.txt",3,4)

http://rosettacode.org/wiki/Remove_lines_from_a_file

Remove lines from a file

Task Remove a specific line or a number of lines from a file. This should be implemented as a routine that takes three parameters (filename, starting line, and the number of lines to be removed). For the purpose of this task, line numbers and the number of lines start at one, so to remove the first two lines from the file foobar.txt, the parameters should be: foobar.txt, 1, 2 Empty lines are considered and should still be counted, and if the specified line is empty, it should still be removed. An appropriate message should appear if an attempt is made to remove lines beyond the end of the file.

#Wren

Wren

import "os" for Platform import "io" for File var removeLines = Fn.new { |fileName, startLine, numLines| if (fileName == "" || startLine < 1 || numLines < 1) Fiber.abort("Invalid argument(s).") if (!File.exists(fileName)) Fiber.abort("Can't find %(fileName).") var text = File.read(fileName) System.print("Contents of %(fileName) before removal:\n%(text)") var sep = Platform.isWindows ? "\r\n" : "\n" var lines = text.split(sep) var size = lines.count if (startLine > size) { System.print("The starting line is beyond the length of the file.") return } var n = numLines if (startLine + numLines - 1 > size) { System.print("Attempting to remove some lines which are beyond the end of the file.") n = size - startLine + 1 } lines = lines.take(startLine - 1).toList + lines.skip(startLine + n - 1).toList text = lines.join(sep) File.create(fileName) { |file| // effectively overwrites the file file.writeBytes(text) } System.print("Contents of %(fileName) after removal of %(numLines) lines starting from line %(startLine):") System.print(File.read(fileName)) } removeLines.call("foobar.txt", 2, 3)

http://rosettacode.org/wiki/Read_entire_file

Read entire file

Task Load the entire contents of some text file as a single string variable. If applicable, discuss: encoding selection, the possibility of memory-mapping. Of course, in practice one should avoid reading an entire file at once if the file is large and the task can be accomplished incrementally instead (in which case check File IO); this is for those cases where having the entire file is actually what is wanted.

#Ol

Ol

(define content (bytes->string (vec-iter (file->vector "file.txt")))) (print content)

http://rosettacode.org/wiki/Read_entire_file

Read entire file

Task Load the entire contents of some text file as a single string variable. If applicable, discuss: encoding selection, the possibility of memory-mapping. Of course, in practice one should avoid reading an entire file at once if the file is large and the task can be accomplished incrementally instead (in which case check File IO); this is for those cases where having the entire file is actually what is wanted.

#ooRexx

ooRexx

file = 'c:\test.txt' myStream = .stream~new(file) myString = myStream~charIn(,myStream~chars)

http://rosettacode.org/wiki/Regular_expressions

Regular expressions

Task match a string against a regular expression substitute part of a string using a regular expression

#Toka

Toka

#! Include the regex library needs regex #! The two test strings " This is a string" is-data test.1 " Another string" is-data test.2 #! Create a new regex named 'expression' which tries #! to match strings beginning with 'This'. " ^This" regex: expression #! An array to store the results of the match #! (Element 0 = starting offset, Element 1 = ending offset of match) 2 cells is-array match #! Try both test strings against the expression. #! try-regex will return a flag. -1 is TRUE, 0 is FALSE expression test.1 2 match try-regex . expression test.2 2 match try-regex .

http://rosettacode.org/wiki/Regular_expressions

Regular expressions

Task match a string against a regular expression substitute part of a string using a regular expression

#TXR

TXR

@(collect) @(coll :gap 0)@mismatch@{match /dog/}@(end)@suffix @(output) @(rep)@{mismatch}cat@(end)@suffix @(end) @(end)

http://rosettacode.org/wiki/Reverse_a_string

Reverse a string

Task Take a string and reverse it. For example, "asdf" becomes "fdsa". Extra credit Preserve Unicode combining characters. For example, "as⃝df̅" becomes "f̅ds⃝a", not "̅fd⃝sa". Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet

#Elixir

Elixir

IO.puts (String.reverse "asdf") IO.puts (String.reverse "as⃝df̅")

http://rosettacode.org/wiki/Reverse_words_in_a_string

Reverse words in a string

Task Reverse the order of all tokens in each of a number of strings and display the result; the order of characters within a token should not be modified. Example Hey you, Bub! would be shown reversed as: Bub! you, Hey Tokens are any non-space characters separated by spaces (formally, white-space); the visible punctuation form part of the word within which it is located and should not be modified. You may assume that there are no significant non-visible characters in the input. Multiple or superfluous spaces may be compressed into a single space. Some strings have no tokens, so an empty string (or one just containing spaces) would be the result. Display the strings in order (1st, 2nd, 3rd, ···), and one string per line. (You can consider the ten strings as ten lines, and the tokens as words.) Input data (ten lines within the box) line ╔════════════════════════════════════════╗ 1 ║ ---------- Ice and Fire ------------ ║ 2 ║ ║ ◄─── a blank line here. 3 ║ fire, in end will world the say Some ║ 4 ║ ice. in say Some ║ 5 ║ desire of tasted I've what From ║ 6 ║ fire. favor who those with hold I ║ 7 ║ ║ ◄─── a blank line here. 8 ║ ... elided paragraph last ... ║ 9 ║ ║ ◄─── a blank line here. 10 ║ Frost Robert ----------------------- ║ ╚════════════════════════════════════════╝ Cf. Phrase reversals

#Tailspin

Tailspin

def input: ['---------- Ice and Fire ------------', '', 'fire, in end will world the say Some', 'ice. in say Some', 'desire of tasted I''ve what From', 'fire. favor who those with hold I', '', '... elided paragraph last ...', '', 'Frost Robert -----------------------'] ; composer words [ <word>* ] rule word: <~WS> <WS>? end words $input... -> '$ -> words -> $(last..first:-1)...; ' -> !OUT::write

http://rosettacode.org/wiki/Reverse_words_in_a_string

Reverse words in a string

Task Reverse the order of all tokens in each of a number of strings and display the result; the order of characters within a token should not be modified. Example Hey you, Bub! would be shown reversed as: Bub! you, Hey Tokens are any non-space characters separated by spaces (formally, white-space); the visible punctuation form part of the word within which it is located and should not be modified. You may assume that there are no significant non-visible characters in the input. Multiple or superfluous spaces may be compressed into a single space. Some strings have no tokens, so an empty string (or one just containing spaces) would be the result. Display the strings in order (1st, 2nd, 3rd, ···), and one string per line. (You can consider the ten strings as ten lines, and the tokens as words.) Input data (ten lines within the box) line ╔════════════════════════════════════════╗ 1 ║ ---------- Ice and Fire ------------ ║ 2 ║ ║ ◄─── a blank line here. 3 ║ fire, in end will world the say Some ║ 4 ║ ice. in say Some ║ 5 ║ desire of tasted I've what From ║ 6 ║ fire. favor who those with hold I ║ 7 ║ ║ ◄─── a blank line here. 8 ║ ... elided paragraph last ... ║ 9 ║ ║ ◄─── a blank line here. 10 ║ Frost Robert ----------------------- ║ ╚════════════════════════════════════════╝ Cf. Phrase reversals

#Tcl

Tcl

set lines { "---------- Ice and Fire ------------" "" "fire, in end will world the say Some" "ice. in say Some" "desire of tasted I've what From" "fire. favor who those with hold I" "" "... elided paragraph last ..." "" "Frost Robert -----------------------" } foreach line $lines { puts [join [lreverse [regexp -all -inline {\S+} $line]]] # This would also work for data this simple: ### puts [lreverse $line] }

http://rosettacode.org/wiki/Rot-13

Rot-13

Task Implement a rot-13 function (or procedure, class, subroutine, or other "callable" object as appropriate to your programming environment). Optionally wrap this function in a utility program (like tr, which acts like a common UNIX utility, performing a line-by-line rot-13 encoding of every line of input contained in each file listed on its command line, or (if no filenames are passed thereon) acting as a filter on its "standard input." (A number of UNIX scripting languages and utilities, such as awk and sed either default to processing files in this way or have command line switches or modules to easily implement these wrapper semantics, e.g., Perl and Python). The rot-13 encoding is commonly known from the early days of Usenet "Netnews" as a way of obfuscating text to prevent casual reading of spoiler or potentially offensive material. Many news reader and mail user agent programs have built-in rot-13 encoder/decoders or have the ability to feed a message through any external utility script for performing this (or other) actions. The definition of the rot-13 function is to simply replace every letter of the ASCII alphabet with the letter which is "rotated" 13 characters "around" the 26 letter alphabet from its normal cardinal position (wrapping around from z to a as necessary). Thus the letters abc become nop and so on. Technically rot-13 is a "mono-alphabetic substitution cipher" with a trivial "key". A proper implementation should work on upper and lower case letters, preserve case, and pass all non-alphabetic characters in the input stream through without alteration. Related tasks Caesar cipher Substitution Cipher Vigenère Cipher/Cryptanalysis Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet

#X86_Assembly

X86 Assembly

format ELF executable 3 entry start segment readable writeable buf rb 1 segment readable executable start: mov eax, 3 ; syscall "read" mov ebx, 0 ; stdin mov ecx, buf ; buffer for read byte mov edx, 1 ; len (read one byte) int 80h cmp eax, 0 ; EOF? jz exit xor eax, eax ; load read char to eax mov al, [buf] cmp eax, "A" ; see if it is in ascii a-z or A-Z jl print cmp eax, "z" jg print cmp eax, "Z" jle rotup cmp eax, "a" jge rotlow jmp print rotup: sub eax, "A"-13 ; do rot 13 for A-Z cdq mov ebx, 26 div ebx add edx, "A" jmp rotend rotlow: sub eax, "a"-13 ; do rot 13 for a-z cdq mov ebx, 26 div ebx add edx, "a" rotend: mov [buf], dl print: mov eax, 4 ; syscall write mov ebx, 1 ; stdout mov ecx, buf ; *char mov edx, 1 ; string length int 80h jmp start exit: mov eax,1 ; syscall exit xor ebx,ebx ; exit code int 80h

http://rosettacode.org/wiki/Roman_numerals/Encode

Roman numerals/Encode

Task Create a function taking a positive integer as its parameter and returning a string containing the Roman numeral representation of that integer. Modern Roman numerals are written by expressing each digit separately, starting with the left most digit and skipping any digit with a value of zero. In Roman numerals: 1990 is rendered: 1000=M, 900=CM, 90=XC; resulting in MCMXC 2008 is written as 2000=MM, 8=VIII; or MMVIII 1666 uses each Roman symbol in descending order: MDCLXVI

#Wren

Wren

var romans = [ [1000, "M"], [900, "CM"], [500, "D"], [400, "CD"], [100, "C"], [90, "XC"], [50, "L"], [40, "XL"], [10, "X"], [9, "IX"], [5, "V"], [4, "IV"], [1, "I"] ] var encode = Fn.new { |n| if (n > 5000 || n < 1) return null var res = "" for (r in romans) { while (n >= r[0]) { n = n - r[0] res = res + r[1] } } return res } System.print(encode.call(1990)) System.print(encode.call(1666)) System.print(encode.call(2008)) System.print(encode.call(2020))

http://rosettacode.org/wiki/Repeat_a_string

Repeat a string

Take a string and repeat it some number of times. Example: repeat("ha", 5) => "hahahahaha" If there is a simpler/more efficient way to repeat a single “character” (i.e. creating a string filled with a certain character), you might want to show that as well (i.e. repeat-char("*", 5) => "*****"). Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet

#MATLAB_.2F_Octave

MATLAB / Octave

function S = repeat(s , n) S = repmat(s , [1,n]) ; return

http://rosettacode.org/wiki/Repeat_a_string

Repeat a string

Take a string and repeat it some number of times. Example: repeat("ha", 5) => "hahahahaha" If there is a simpler/more efficient way to repeat a single “character” (i.e. creating a string filled with a certain character), you might want to show that as well (i.e. repeat-char("*", 5) => "*****"). Other tasks related to string operations: Metrics Array length String length Copy a string Empty string (assignment) Counting Word frequency Letter frequency Jewels and stones I before E except after C Bioinformatics/base count Count occurrences of a substring Count how many vowels and consonants occur in a string Remove/replace XXXX redacted Conjugate a Latin verb Remove vowels from a string String interpolation (included) Strip block comments Strip comments from a string Strip a set of characters from a string Strip whitespace from a string -- top and tail Strip control codes and extended characters from a string Anagrams/Derangements/shuffling Word wheel ABC problem Sattolo cycle Knuth shuffle Ordered words Superpermutation minimisation Textonyms (using a phone text pad) Anagrams Anagrams/Deranged anagrams Permutations/Derangements Find/Search/Determine ABC words Odd words Word ladder Semordnilap Word search Wordiff (game) String matching Tea cup rim text Alternade words Changeable words State name puzzle String comparison Unique characters Unique characters in each string Extract file extension Levenshtein distance Palindrome detection Common list elements Longest common suffix Longest common prefix Compare a list of strings Longest common substring Find common directory path Words from neighbour ones Change e letters to i in words Non-continuous subsequences Longest common subsequence Longest palindromic substrings Longest increasing subsequence Words containing "the" substring Sum of the digits of n is substring of n Determine if a string is numeric Determine if a string is collapsible Determine if a string is squeezable Determine if a string has all unique characters Determine if a string has all the same characters Longest substrings without repeating characters Find words which contains all the vowels Find words which contains most consonants Find words which contains more than 3 vowels Find words which first and last three letters are equals Find words which odd letters are consonants and even letters are vowels or vice_versa Formatting Substring Rep-string Word wrap String case Align columns Literals/String Repeat a string Brace expansion Brace expansion using ranges Reverse a string Phrase reversals Comma quibbling Special characters String concatenation Substring/Top and tail Commatizing numbers Reverse words in a string Suffixation of decimal numbers Long literals, with continuations Numerical and alphabetical suffixes Abbreviations, easy Abbreviations, simple Abbreviations, automatic Song lyrics/poems/Mad Libs/phrases Mad Libs Magic 8-ball 99 Bottles of Beer The Name Game (a song) The Old lady swallowed a fly The Twelve Days of Christmas Tokenize Text between Tokenize a string Word break problem Tokenize a string with escaping Split a character string based on change of character Sequences Show ASCII table De Bruijn sequences Self-referential sequences Generate lower case ASCII alphabet

#Maxima

Maxima

"$*"(s, n) := apply(sconcat, makelist(s, n))$ infix("$*")$ "abc" $* 5; /* "abcabcabcabcabc" */

http://rosettacode.org/wiki/Remove_duplicate_elements

Remove duplicate elements

Sorting Algorithm This is a sorting algorithm. It may be applied to a set of data in order to sort it. For comparing various sorts, see compare sorts. For other sorting algorithms, see sorting algorithms, or: O(n logn) sorts Heap sort | Merge sort | Patience sort | Quick sort O(n log2n) sorts Shell Sort O(n2) sorts Bubble sort | Cocktail sort | Cocktail sort with shifting bounds | Comb sort | Cycle sort | Gnome sort | Insertion sort | Selection sort | Strand sort other sorts Bead sort | Bogo sort | Common sorted list | Composite structures sort | Custom comparator sort | Counting sort | Disjoint sublist sort | External sort | Jort sort | Lexicographical sort | Natural sorting | Order by pair comparisons | Order disjoint list items | Order two numerical lists | Object identifier (OID) sort | Pancake sort | Quickselect | Permutation sort | Radix sort | Ranking methods | Remove duplicate elements | Sleep sort | Stooge sort | [Sort letters of a string] | Three variable sort | Topological sort | Tree sort Given an Array, derive a sequence of elements in which all duplicates are removed. There are basically three approaches seen here: Put the elements into a hash table which does not allow duplicates. The complexity is O(n) on average, and O(n2) worst case. This approach requires a hash function for your type (which is compatible with equality), either built-in to your language, or provided by the user. Sort the elements and remove consecutive duplicate elements. The complexity of the best sorting algorithms is O(n log n). This approach requires that your type be "comparable", i.e., have an ordering. Putting the elements into a self-balancing binary search tree is a special case of sorting. Go through the list, and for each element, check the rest of the list to see if it appears again, and discard it if it does. The complexity is O(n2). The up-shot is that this always works on any type (provided that you can test for equality).

#jq

jq

[4,3,2,1,1,2,3,4] | unique

http://rosettacode.org/wiki/Reduced_row_echelon_form

Reduced row echelon form

Reduced row echelon form You are encouraged to solve this task according to the task description, using any language you may know. Task Show how to compute the reduced row echelon form (a.k.a. row canonical form) of a matrix. The matrix can be stored in any datatype that is convenient (for most languages, this will probably be a two-dimensional array). Built-in functions or this pseudocode (from Wikipedia) may be used: function ToReducedRowEchelonForm(Matrix M) is lead := 0 rowCount := the number of rows in M columnCount := the number of columns in M for 0 ≤ r < rowCount do if columnCount ≤ lead then stop end if i = r while M[i, lead] = 0 do i = i + 1 if rowCount = i then i = r lead = lead + 1 if columnCount = lead then stop end if end if end while Swap rows i and r If M[r, lead] is not 0 divide row r by M[r, lead] for 0 ≤ i < rowCount do if i ≠ r do Subtract M[i, lead] multiplied by row r from row i end if end for lead = lead + 1 end for end function For testing purposes, the RREF of this matrix: 1 2 -1 -4 2 3 -1 -11 -2 0 -3 22 is: 1 0 0 -8 0 1 0 1 0 0 1 -2

#R

R

rref <- function(m) { pivot <- 1 norow <- nrow(m) nocolumn <- ncol(m) for(r in 1:norow) { if ( nocolumn <= pivot ) break; i <- r while( m[i,pivot] == 0 ) { i <- i + 1 if ( norow == i ) { i <- r pivot <- pivot + 1 if ( nocolumn == pivot ) return(m) } } trow <- m[i, ] m[i, ] <- m[r, ] m[r, ] <- trow m[r, ] <- m[r, ] / m[r, pivot] for(i in 1:norow) { if ( i != r ) m[i, ] <- m[i, ] - m[r, ] * m[i, pivot] } pivot <- pivot + 1 } return(m) } m <- matrix(c(1, 2, -1, -4, 2, 3, -1, -11, -2, 0, -3, 22), 3, 4, byrow=TRUE) print(m) print(rref(m))

http://rosettacode.org/wiki/Real_constants_and_functions

Real constants and functions

Task Show how to use the following math constants and functions in your language (if not available, note it): e (base of the natural logarithm) π {\displaystyle \pi } square root logarithm (any base allowed) exponential (ex ) absolute value (a.k.a. "magnitude") floor (largest integer less than or equal to this number--not the same as truncate or int) ceiling (smallest integer not less than this number--not the same as round up) power (xy ) Related task Trigonometric Functions

#Metafont

Metafont

show mexp(256); % outputs e; since MF uses mexp(x) = exp(x/256) show 3.14159; % no pi constant built in; of course we can define it % in several ways... even computing % C/2r (which would be funny since MF handles paths, % and a circle is a path...) show sqrt2; % 1.41422, or in general sqrt(a) show mexp(256*x); % see e. show abs(x); % returns |x| (the absolute value of the number x, or % the length of the vector x); it is the same as % length(x); plain Metafont in fact says: % let abs = length; show floor(x); % floor show ceiling(x); % ceiling show x**y; % ** is not a built in: it is defined in the basic macros % set for Metafont (plain Metafont) as a primarydef

http://rosettacode.org/wiki/Real_constants_and_functions

Real constants and functions

Task Show how to use the following math constants and functions in your language (if not available, note it): e (base of the natural logarithm) π {\displaystyle \pi } square root logarithm (any base allowed) exponential (ex ) absolute value (a.k.a. "magnitude") floor (largest integer less than or equal to this number--not the same as truncate or int) ceiling (smallest integer not less than this number--not the same as round up) power (xy ) Related task Trigonometric Functions

#min

min

e ; e pi ; π sqrt ; square root log10 ; common logarithm log2 ; binary logarithm ; no exponential ; no absolute value floor ; greatest whole number smaller than or equal ceil ; smallest whole number greater than or equal trunc ; remove the fractional part (i.e. round towards 0) round ; round number to nth decimal place pow ; power

http://rosettacode.org/wiki/Remove_lines_from_a_file

Remove lines from a file

Task Remove a specific line or a number of lines from a file. This should be implemented as a routine that takes three parameters (filename, starting line, and the number of lines to be removed). For the purpose of this task, line numbers and the number of lines start at one, so to remove the first two lines from the file foobar.txt, the parameters should be: foobar.txt, 1, 2 Empty lines are considered and should still be counted, and if the specified line is empty, it should still be removed. An appropriate message should appear if an attempt is made to remove lines beyond the end of the file.

#zkl

zkl

fcn deleteLinesM(fname, start,num){ blob:=File(fname).read(); // file to memory n:=blob.seek(Void,start-1); // seek to line and remember it blob.del(n,blob.seek(Void,num)-n); File.stdout.write(blob); } deleteLinesM("nn.zkl", 2,5);

http://rosettacode.org/wiki/Read_entire_file

Read entire file

Task Load the entire contents of some text file as a single string variable. If applicable, discuss: encoding selection, the possibility of memory-mapping. Of course, in practice one should avoid reading an entire file at once if the file is large and the task can be accomplished incrementally instead (in which case check File IO); this is for those cases where having the entire file is actually what is wanted.

#Oz

Oz

declare FileHandle = {New Open.file init(name:"test.txt")} FileContents = {FileHandle read(size:all list:$)} in {FileHandle close} {System.printInfo FileContents}

http://rosettacode.org/wiki/Read_entire_file

Read entire file

Task Load the entire contents of some text file as a single string variable. If applicable, discuss: encoding selection, the possibility of memory-mapping. Of course, in practice one should avoid reading an entire file at once if the file is large and the task can be accomplished incrementally instead (in which case check File IO); this is for those cases where having the entire file is actually what is wanted.

#Panda

Panda

file:readme.txt .text

http://rosettacode.org/wiki/Regular_expressions

Regular expressions

Task match a string against a regular expression substitute part of a string using a regular expression

#UNIX_Shell

UNIX Shell

s="I am a string" if [[ $s =~ str..g$ ]]; then echo "the string ends with 'str..g'" fi