题解 | #加减乘除#

#include<string>
#include<algorithm>
using namespace std;
#define MAX 100
//阶乘
long long int f1(int n) {
	long long int res = 1;
	for (int i = 1; i <= n; i++) {
		res *= i;
	}
	return res;
}
int main() {
	int a, b;
	char c;
	while (cin >> a) {
		cin >> c;
		if (c == '!') {
			cout << f1(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 == '/')&(b!=0)) {
				cout << a / b << endl;
			}
			else if ((c == '%')&(b != 0)) {
				cout << a % b << endl;
			}
			else {
				cout << "error" << endl;
			}
		}
	}

	return 0;
}