题解 | 加减乘除

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <string>

using namespace std;

int a, b;
char s;

//复习一下getline()函数 getline(cin, 字符串变量)

int main() {
    //重点是阶乘的输入怎么处理
    while (cin >> a >> s) {
        if (s == '!') {
            if (a == 0) {
                cout << 1 << endl;
                break;
            }
            else {
                int res = 1;
                for (int i = 1; i <= a; i++) {
                    res *= i;
                }
                cout << res << endl;
            }
        }
        else {
            cin >> b;
            if (s == '+') cout << a + b << endl;
            else if (s == '-') cout << a - b << endl;
            else if (s == '*') cout << a * b << endl;
            else if (s == '/') {
                if (b == 0) {
                    cout << "error" << endl;
                    break;
                }
                else {
                    cout << a / b << endl;
                }
            }
            else {
                if (b == 0) {
                    cout << "error" << endl;
                    break;
                }
                else {
                    cout << a % b << endl;
                }
            }
        }
    }
    return 0;   
}