What's ending comma in print function for?

Question

This code is from http://docs.python.org/2/tutorial/errors.html#predefined-clean-up-actions

with open("myfile.txt") as f:     for line in f:         print line, 

What I don't understand is what's that , for at the end of print command.

I also checked doc, http://docs.python.org/2/library/functions.html#print.

Not understanding enough, is it a mistake?(it seems not. it's from the official tutorial).

I am from ruby/javascript and it's unusual for me.

Answer 1

In python 2.7, the comma is to show that the string will be printed on the same line

For example:

for i in xrange(10):      print i, 

This will print

1 2 3 4 5 6 7 8 9  

To do this in python 3 you would do this:

 for i in xrange(10):       print(i,end=" ") 

You will probably find this answer helpful

Printing horizontally in python

---- Edit ---

The documentation, http://docs.python.org/2/reference/simple_stmts.html#the-print-statement, says

A '\n' character is written at the end, unless the print statement ends with a comma.

Answer 2

It prevents the print from ending with a newline, allowing you to append a new print to the end of the line.

Python 3 changes this completely and the trailing comma is no longer accepted. You use the end parameter to change the line ending, setting it to a blank string to get the same effect.