Python Function Won't Return Value

Question

I'm trying to create a recursive function in Python (as part of an online course) which takes two numbers and returns the highest common denominator between them, however, the function won't return the value.

My code is:

def gcdRecur(a, b):
    x = min(a,b)
    y = max(a, b)
    if x == 0:
        return y
    else:
        gcdRecur(x, y%x)

When I test the function with gcdRecur(2,12) or gcdRecur(6,12) nothing is returned. I know the function works because if I print y before I return it then the correct denominator is printed to the console, I'm just not sure why the function doesn't output y.

It's probably something obvious but as I'm new to Python I'm not sure what I'm doing wrong.

Any help would be much appreciated.

In some languages, the return value of a function is the value of the last evaluated expression. Python isn't one of those languages. — chepner, Jun 16 '20 at 16:03
`def gcd(A,B): return A if B==0 else gcd(B,A%B)` , that is more beautiful and simple way to implement gcd in one line — just-Luka, Jun 16 '20 at 16:07

score 3 · Accepted Answer · answered Jun 16 '20 at 16:02

3

You need to return something in both branches:

else:
    return gcdRecur(x, y%x)

answered Jun 16 '20 at 16:02

tzaman

46,925
11
90
115

Python Function Won't Return Value

1 Answers1