Converting a string to lower-case (without built-in to-lower functions!) The goal of this code-golf is to create a code that lets the user input an ASCII string (contains only printable ASCII characters), and your program outputs the lower-case variant of this string.
Important: you are NOT allowed to use a built-in function that converts the string (or just one character) to lowercase (such as ToLower() in .NET, strtolower() in PHP
, ...)! You're allowed to use all other built-in functions, however.
Another important note: The input string doesn't contain only uppercase characters. The input string is a mix of uppercase characters, lowercase characters, numbers and other ASCII printable characters.
Good luck!
Python 2.7 - 30 (with terrible and unapologetic rule abuse)

raw_input().upper().swapcase()


As an anonymous edit pointed out, you can do it in 27 26 in Python 3:

input().upper().swapcase()


I'm flagrantly abusing the rules here, but...


  Important: you are NOT allowed to use a built-in function that converts the string (or just one character) to lowercase (such as ToLower() in .NET, strtolower() in PHP 
  , ...)! You're allowed to use all other built-in functions, however.  


This takes the strings and coverts it to upper case. Then in a very unrelated method call, it reverses the case of the string - so that any lower case letters become upper case letters... and swaps any upper case letters to lower case letters.