Why am I getting a "None" at the end of the output while computing textwrap module in Python?

Question

Although I am defining my function as below:

import textwrap

def wrap(string, max_width):
    print(textwrap.fill(string, max_width))

if __name__ == '__main__':
    string, max_width = input(), int(input())
    result = wrap(string, max_width)
    print(result)

I am getting an error like:

*ABCD
EFGH
IJKL
IMNO
QRST
UVWX
YZ
None*

Can you please help me to debug why this "None" or how is this value getting augmented with the output.

Please provide a [mcve] that reproduces the output you show. When I run your code, I get an error because `textwrap` is undefined. — Code-Apprentice, Apr 01 '20 at 19:16
Most likely you get `None` because `textwrap.fill()` does not have a `return` statement so it returns `None` by default which is then printed by the `print()` call in the `wrap` function you show here. — Code-Apprentice, Apr 01 '20 at 19:18
Yeah, I made the code more specific and clear now. @Stqrosta — ANKAN, Apr 01 '20 at 19:20
This is just the classic "function without an explicit return returns none" issue. — AMC, Apr 01 '20 at 20:19

score 1 · Accepted Answer · answered Apr 01 '20 at 19:23

You are printing twice. Once in the function, and then again the return value of the function. The None is coming from the second print.

Do this:

import textwrap

def wrap(string, max_width):
    return textwrap.fill(string, max_width) # return , don't print

if __name__ == '__main__':
    string, max_width = input().rstrip(), int(input())
    result = wrap(string, max_width)
    print(result)

score 0 · Answer 2 · answered Apr 01 '20 at 19:24

you forgot to retun the result:

this should work:

import textwrap

def wrap(string, max_width):
    return(textwrap.fill(string, max_width))

if __name__ == '__main__':
    string, max_width = input(), int(input())
    result = wrap(string, max_width)
    print(result)

score 0 · Answer 3 · answered Apr 01 '20 at 20:11

0

wrap() does not have an explicit return. By default it returns None. So the value of result is None. Just get rid of the result variable and the following print() to fix it. Alternatively, change wrap() to return the result instead of printing it.

answered Apr 01 '20 at 20:11

Code-Apprentice

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Why am I getting a "None" at the end of the output while computing textwrap module in Python?

3 Answers3