(python3) what happend to my recursion function?? why it does not return varieable?

Question

n, m = map(int, input().split())
if n < m:
    n, m = m, n

def mod(x,y):
    if x % y:
        mod(y, x % y)
    else:
        return y
        #or return(y) or return (y)

print(mod(n, m))

I'm try to make recursive function to get greatest common divisor and least common multiple, but the function does not return the variable.

I checked a variable is fine (it's exist well right before return function) and if statement is also fine but the return() function does nothing but return None.

I tried return string (return "what") but it still returns None.

Where is my mistake? And how to make return function returns variable normally?

Inside mod, you are _calling_ mod but not _returning_ the value. — John Gordon, Dec 14 '21 at 02:21

score 1 · Answer 1 · answered Dec 14 '21 at 02:35

1

def mod(x,y):
    if x % y:
        return mod(y, x % y)
    else:
        return y

answered Dec 14 '21 at 02:35

Ming

479
2
11

i edited it! but it is still not working – 김철수철수 Dec 14 '21 at 02:53
It works for me. Try `print(mod(20, 30))` ? – Ming Dec 14 '21 at 02:59
yep. i tried both enviroment python idle(3.9.9) and vscode. It returns None. (sad emoji) – 김철수철수 Dec 14 '21 at 03:25
https://www.mycompiler.io/view/00QstPl Run this. It prints `10` – Ming Dec 14 '21 at 03:33

score 0 · Answer 2 · answered Dec 14 '21 at 02:30

0

You are returing "y" which is a string instead you should

 return y

which is a variable

answered Dec 14 '21 at 02:30

Satyam Shankar

250
2
12

That appears to have been an irrelevant typo. – Carcigenicate Dec 14 '21 at 02:36
eh.... i did edit my code but it still return nothing. – 김철수철수 Dec 14 '21 at 02:48

(python3) what happend to my recursion function?? why it does not return varieable?

2 Answers2