用c++帮我写一个计算器

当然，下面是一个简单的控制台版的四则运算计算器的C++代码示例：

#include <iostream>
using namespace std;

// 函数来获取用户输入并返回计算结果
double calculate(double num1, char op, double num2) {
    switch(op) {
        case '+':
            return num1 + num2;
        case '-':
            return num1 - num2;
        case '*':
            return num1 * num2;
        case '/':
            if(num2 != 0)
                return num1 / num2;
            else
                throw "Error! Division by zero is not allowed.";
        default:
            cout << "Invalid operator!";
            return 0;
    }
}

int main() {
    double num1, num2;
    char operation;

    cout << "Enter first number: ";
    cin >> num1;
    
    cout << "Enter an operator (+, -, *, /): ";
    cin >> operation;

    cout << "Enter second number: ";
    cin >> num2;

    try {
        double result = calculate(num1, operation, num2);
        cout << "The result is: " << result << endl;
    } catch(const char* msg) {
        cerr << msg << endl;
    }

    return 0;
}

这个程序首先提示用户输入两个数字和一个运算符，然后根据运算符执行相应的数学运算。如果用户输入了无效的运算符或者除数为零，程序会捕获异常并显示错误消息。