题解 | 加减乘除

#include <bits/stdc++.h>
using namespace std;

int getFac(int x) {
    int ans = 1;
    while (x != 0) {
        ans *= x;
        x--;
    }
    return ans;
}


int main() {
    int a, b;
    char c;
    while (cin >> a) {
        cin >> c;
        if (c == '!') {
            cout << getFac(a)<<endl;
        } else {
            cin >> b;
            if (c == '+')cout << a + b << endl;
            else if (c == '-')cout << a - b << endl;
            else if (c == '*')cout << a* b << endl;
            else if (c == '/') {
                if (b == 0)cout << "error" << endl;
                else cout << a / b << endl;
            } else if (c == '%') {
                if (b == 0)cout << "error" << endl;
                else cout << a % b << endl;
            }
        }
    }
}

不等长获取，加上个条件判断即可