Python output from print(print(print('aaa')))

Question

I don\'t quite understand output received from:

print(print(print(\'aaa\')))

aaa

None

None

F

Answer 1

In python, when a function returns nothing explicitly, it returns None.

A function like print does an action but is not supposed to return anything, so it returns None. The print function could be something like this:

import sys


def print(*args, sep=' ', end='\n', file=sys.stdout, flush=False)
    for arg in args:
        file.write(str(arg))
        if arg is not args[-1]:
            file.write(str(sep))
    file.write(str(end))
    if flush:
        sys.stdout.flush()

Which is equivalent to:

def print(*args, sep=' ', end='\n', file=sys.stdout, flush=False):
    # The same code
    return None

And in both cases you will get

>>> print('Hello world')
Hello world
>>> print(print('Hello world'))
Hello world
None

Hope this helps.