can you understand why this code prints None?

can you understand why this code prints None? - Printable Version

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can you understand why this code prints None? - arcbal - Mar-13-2019

# assuming n is always greater than m
def fd(n,m):
    if n%m==0:
        print(m)
        return m
    else:
        print(n,m)
        fd(n,(m-1))
print(fd(6,5))

the result is not what i expect,i expect

Output:6,5
6,4
3
3

but the result i get is:

Output:6,5
6,4
3
None

i don't why this None is occurring??

RE: can you understand this code? - ichabod801 - Mar-13-2019

If n % m == 0, then there is a return statement. But if n % m != 0, there is no return statement. In that case, the default return of None is done by Python. You probably want line 8 to be:

return fd(n, m - 1)   # you don't need parentheses for m - 1.

RE: can you understand this code? - arcbal - Mar-13-2019

you are awesome,thanks.

(Mar-13-2019, 02:53 AM)ichabod801 Wrote: If n % m == 0, then there is a return statement. But if n % m != 0, there is no return statement. In that case, the default return of None is done by Python. You probably want line 8 to be:
 return fd(n, m - 1) # you don't need parentheses for m - 1. 

you are the best, thanks.