Understanding an error in a recursive function?

Question

I am trying to write a recursive function, but get an error in the line : n + sum(n-1); My compiler is German, so a poor translation of the error message would be: "void value not ignored as supposed to". Thanks for help!

void sum (int n)
{
    if(n==0)
    {
        cout << n << endl;
    }
    else if(n>0)
    {
        n + sum(n-1);
        cout << n << endl;
    }
}

int main()
{
   sum(3);
   return 0;
}

Answer 1

Notice that you've defined the function as

void sum (int n);

This function has no return value. However, in this code:

n + sum(n-1);

You are trying to add n to the return value of sum(n - 1), which isn't legal because sum(n - 1) doesn't produce a value.

To fix this, you probably will want to change the function so that it returns an int. If you do this, you'll need to make other changes, such as adding return statements into the function, but it should help get you on the right track.

Hope this helps!

Answer 2

your sum method returns void, change it to int

int sum (int n)