print() 2 variables in Python 3.3

Question

I'm learning python and came across this behavior which puzzles me.

Why does this code print out the variables enclosed by parenthesis and \r\n:

def print_a_line(line_count, f):
    print(line_count, f.readline())

current_line = 1
print_a_line(current_line, current_file)

Prints:

(1, 'a1\r\n')

while this code:

def print_a_line(line_count, f):
    print(f.readline())

current_line = 1
print_a_line(current_line, current_file)

prints without the parenthesis:

a1

Answer 1

In the first case, when you print(line_count, f.readline()) you are actually saying print a tuple, which first element is line_count and the second element is f.readline(), f.readline() reads the entire line, with the end of line marker, in your file it is '\r\n'.

In the second case, print (f.readline()), you are printing just a string, not a tuple containing a string, (if you want a tuple containing just a string you should use (mystring,).

The (anystring) notation allows you to use:

mystring = ('This is my '
            'very long string')

Instead of print(line_count, f.readline()) you should use

print (str(line_count) + f.readline())

or

print ('%d %s'%(line_count, f.readline()))