Recursive function that returns the sum of the digits of a number

Question

I need to create a recursive function that takes a number n integer and returns the sum of the digits of this number.

I made the following code but it’s giving None:

def somadig(n, s = 0):
    if n > 10:
       d = n%10
       s += d
       return somadig(n//10,s)


print(somadig(120))

Answer 1

You are not treating the output correctly. When n reach 0 must return 0, otherwise you must make the account and cause recursion. There are too many variables and steps in the code, work with the sum directly instead of storing in variable and pass again, simplifying:

def somadig(n):
    if n == 0:
        return 0
    else:
        return (n % 10) + somadig(n // 10)

print(somadig(120))

Behold working in the ideone. And in the repl it.. Also put on the Github for future reference.

His giving None because if the condition of if is false does not pass through a return, so it returns nothing.