题解 | 加减乘除

#include<cstdio>
#include<iostream>
#include<string>
using namespace std;
void add(int a, int b) { //加法
    cout << a + b << endl;
}
void sub(int a, int b) { //减法

    cout << a - b << endl;
}
void mul(int a, int b) { //乘法

    cout << a* b << endl;
}
void divide(int a, int b) { //除法
    if (a == 0 || b == 0) {
        cout << "error" << endl;
    } else {
        cout << a / b << endl;
    }
}
void qy(int a, int b) { //取余
    if (a == 0 || b == 0) {
        cout << "error" << endl;
    } else {
        cout << a % b << endl;
    }
}
void jc(int a) { //阶乘
    int sum = 1;
    while (a) {
        sum = sum * a;
        a--;
    }
    cout << sum << endl;
}
int main() {
    string c;
    int a = 0;
    int b = 0;
    char d = 'x';
    while (cin >> a) {
        cin >> d;
        if (d == '+') {
            cin >> b;
            add(a, b);
            continue;
        }
        if (d == '-') {
            cin >> b;
            sub(a, b);
            continue;
        }
        if (d == '*') {
            cin >> b;
            mul(a, b);
            continue;
        }
        if (d == '/') {
            cin >> b;
            divide(a, b);
            continue;
        }
        if (d == '%') {
            cin >> b;
            qy(a, b);
            continue;
        }
        if (d == '!') { //阶乘

            jc(a);
            continue;
        }
    }
    return 0;
}