user input and error handling the basic way to read file in python is to use the function openwhich takes file name as an argument the following code illustrates its useinfile open('data txt'' 'for line in infiledo something with line infile close(open file close file herethe first line opens the file data txt for readingas specified with the letter rand creates file object named infile if we want to open file for writingwhich we will consider laterwe have to use open('data txt',' 'the default is rsoto read file we could also simply write infile open('data txt'howeverincluding the can be good habitsince it makes the purpose of the line more obvious to anyone reading the code in the second linewe enter regular for loopwhich will treat the object infile as list-like object and step through the file line by line for each pass through the for loopa single line of the file is read and stored in the string variable lineand inside the for loop we add any code we want for processing this line when there are no more lines in the filethe for loop endsjust as when looping over regular list the final lineinfile close()closes the file and makes it unavailable for further reading this line is not very important when reading from filesbut it is good habit to always include itsince it can make difference when writing to files to return to the concrete data file abovesay the only processing we want is to compute the mean value of the numbers in the file the complete code could look like thisinfile open('data txt'' 'open file mean lines for line in infilenumber float(lineline is string mean mean number lines + mean mean/lines print( 'the mean value is {mean}'this is standard way to read files in pythonbutas usualin programming there are multiple ways to do things an alternative way of opening filewhich many will consider more modernis by using the following codewith open('data txt'' 'as infilefor line in infiledo something with line open file the first lineusing with and as probably does not look familiarbut it does essentially the same thing as the line infile openin the first example one important difference is thatif we use with we see that all file reading and processing must be put inside an indented block of codeand the file is automatically closed when this block has been completed therefore