Why does my code return 'None' along with the correct output?

February 12, 2023

I have a program that takes 4 number inputs and passes them to a user defined function. the first value becomes the second in the list, and the 4th value becomes the third in the list. The program is supposed to output the inputs as numbers with spaces in between them.

def swap_values(user_val1, user_val2, user_val3, user_val4):
    newList = [user_val2, user_val1, user_val4, user_val3]
    return print(f'{newList[0]} {newList[1]} {newList[2]} {newList[3]}')

if __name__ == '__main__': 
    val1 = int(input())
    val2 = int(input())
    val3 = int(input())
    val4 = int(input())
    print(swap_values(val1, val2, val3, val4))

While I do get the correct answer outputted for the input "8, 3, 4, 2", I also get ‘None’ right bellow it like so

3 8 2 4
None

What should I do to fix this?

>Solution :

This is because the function swap_values is first printing the value and returning the print function which is None
This can be fixed by using this code:

def swap_values(user_val1, user_val2, user_val3, user_val4):
newList = [user_val2, user_val1, user_val4, user_val3]
return f'{newList[0]} {newList[1]} {newList[2]} {newList[3]}'

if __name__ == '__main__': 
    val1 = int(input("val1"))
    val2 = int(input("val2"))
    val3 = int(input("val3"))
    val4 = int(input("val4"))
    print(swap_values(val1, val2, val3, val4))