简单

真不骗你，直接复制粘贴就好了

#include<bits/stdc++.h>
using namespace std;
int main(){
    double a, b;
    string p;
    cin >> a >> b >> p;
    if(p == "+") cout << a + b;
    else if(p == "-") cout << a - b;
    else if(p == "*") cout << a * b;
    else if(p == "/"){
        if(b != 0) cout << a / b;
        else cout << "Divided by zero!";
    }else cout << "Invalid operator!";
}