Recursive function for digit sum in c++

Question

Tried writing a recursive function for digit sum in c++ ; ended up getting the last digit instead. Can anyone suggest fixes.. '''

#include<iostream>
using namespace std;

int dsum (int n, int sum)
{
    if(n>0)
    {
        sum = sum + (n%10);
        n = n/10;
        return(n ,sum);
    }
    else return sum;

}

int main()
{
    int i = 345;
    int s = dsum (i,0);
    cout<<"Sum is "<<s;
    return 0;
}

'''

There is no recursion. `return (n,sum)` -> `return dsum(n,sum)`. Voting to close as typo — 463035818_is_not_an_ai, Oct 20 '21 at 08:51
pay attention to warnings: https://godbolt.org/z/b6sxjhzMK. For comma operator: https://stackoverflow.com/questions/54142/how-does-the-comma-operator-work — 463035818_is_not_an_ai, Oct 20 '21 at 08:53

score 0 · Accepted Answer · answered Oct 20 '21 at 09:06

0

You didn't call the recursion as seen in here:

int dsum (int n, int sum)
{
    if(n>0)
    {
        sum = sum + (n%10);
        n = n/10;
        return(n ,sum); // <-- this line
    }
    else return sum;

}

Notice you return(n ,sum); instead of return dsum(n ,sum);. return(n ,sum); fist evaluates the left operand: n and then the right operand: sum. Since there's nothing to evaluates, it will returns the result of the right operand, which is sum.

answered Oct 20 '21 at 09:06

justANewb stands with Ukraine

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What do you mean by " Since there's nothing to evaluates"? – Bathsheba Oct 20 '21 at 10:07
@Bathsheba I mean that there’s no change to n and sum – justANewb stands with Ukraine Oct 20 '21 at 10:28

Recursive function for digit sum in c++

1 Answers1