곱하기 혹은 더하기: 문제 조건

#include <iostream>

using namespace std;

int main()
{
    string str;

    cin >> str;
    cout << "str = " << str << endl;

    int answer = (int(str[0]) - '0');
    int number = 0;

    for(int i=1; i<str.length(); i++)
    {
        number = (int(str[i]) - '0');

        // 0
        if(str[i] == '0' || answer == 0)
        {
            answer += number;
        }
        // 1~9
        else if(str[i] > '1' && str[i] < '9')
        {
            answer *= number;
        }
    }

    cout << "answer = " << answer << endl;

    return 0;
}