Question

Write a recursive function Programming: to_number that forms the integer sum of all digit characters in a string. For example, the result of to_number("3ac4") would be 7.

C++

i know this has been answered before but I keep getting 0 when I enter a string.

Answer 1

#include <iostream>
#include <string>

using namespace std;

int to_number(string s) {
    if (s.length() == 0) {
        return 0;
    } else {
        int num = to_number(s.substr(1));
        if (s[0] >= '0' && s[0] <= '9')
            num += s[0] - '0';
        return num;
    }
}

int main() {
    string s;
    cout << "Enter a string: ";
    cin >> s;
    cout << to_number(s) << endl;
    return 0;
}