Input statement is resulting with None

Question

I'm trying to call a function within a function that asks for some input. It runs and gives me the right answer, but not before showing "None".

def func1(f_temp):
    c_temp = round(float((f_temp - 32) * 5 / 9),1)
    print(f_temp, "degrees Fahrenheit is equal to", c_temp, "degrees Celsius.")

def func2(mph):
    mps = mph * 0.44704
    print(mph, "miles per hour is equal to", mps, "meters per second.")

def main():
    print("Enter 1 to convert Fahrenheit temperature to Celsius.")
    print("Enter 2 to convert speed from miles per hour to meters per second.")
    main_input = int(input())
    if main_input == 1:
        f_temp = input(print("Please enter a temperature in Fahrenheit: "))
        return func1(f_temp)
    elif main_input == 2:
        mph = input(print("Please enter a speed in miles per hour: "))
        return func2(mph)
    else:
        print("Please enter 1 or 2 only.")

And here is what happens when I run it:

main()
Enter 1 to convert Fahrenheit temperature to Celsius.
Enter 2 to convert speed from miles per hour to meters per second.
1
Please enter a temperature in Fahrenheit: 
None52
52.0 degrees Fahrenheit is equal to 11.1 degrees Celsius.

Change `input(print(...))` to just `input(...)`. `print` returns `None`. `input` will print its argument. — Mark Tolonen, Oct 16 '22 at 22:48
I tried taking out 'print' but now i'm getting "TypeError: can't multiply sequence by non-int of type 'float'" — sidewaysblue, Oct 16 '22 at 23:00

score 0 · Answer 1 · answered Oct 16 '22 at 22:51

Change input(print(...)) to just input(...). Print returns None and input() is printing it. (as what @Mark Tolonen said)

def func1(f_temp):
    c_temp = round(float((f_temp - 32) * 5 / 9),1)
    print(f_temp, "degrees Fahrenheit is equal to", c_temp, "degrees Celsius.")

def func2(mph):
    mps = mph * 0.44704
    print(mph, "miles per hour is equal to", mps, "meters per second.")

def main():
    print("Enter 1 to convert Fahrenheit temperature to Celsius.")
    print("Enter 2 to convert speed from miles per hour to meters per second.")
    main_input = int(input())
    if main_input == 1:
        print("Please enter a temperature in Fahrenheit: ", end="")
        f_temp = input()
        return func1(f_temp)
    elif main_input == 2:
        print("Please enter a speed in miles per hour: ", end="")
        mph = input()
        return func2(mph)
    else:
        print("Please enter 1 or 2 only.")

score 0 · Accepted Answer · answered Oct 16 '22 at 22:56

The input() function receive a string and print it, the print() function print a string in the terminal but returns nothing (None),

f_temp = input(print("Please enter a temperature in Fahrenheit: "))

you are calling print inside input, so input waits for a string and only gets a None and print it, this is why your program writes None in some point. You can fix it :

f_temp = input("Please enter a temperature in Fahrenheit: ")

Input statement is resulting with None

2 Answers2