「SuperOJ 213」数字分离

#include <bits/stdc++.h>
using namespace std;
stringstream ssm;
string num;
int sum;
int main() {
    ios::sync_with_stdio(false);
    cin.tie(NULL);
    cin >> num;
    for (register int i = 0, range = num.length(), tmp; i < range; i++)
        ssm << num[i], ssm>>tmp, ssm.clear(), sum += tmp;
    cout << sum;
}