C++用switch语句编写一个简单的实数四则运算程序

在C++中，你可以使用`switch`语句结合`enum`来编写一个简单的实数四则运算程序。首先，你需要创建一个枚举来表示运算符，并定义对应的函数。这里是一个示例：

#include <iostream>
using namespace std;

// 定义运算符枚举
enum Operation {
    ADD,
    SUBTRACT,
    MULTIPLY,
    DIVIDE
};

// 根据运算符执行相应的操作
double applyOperation(double num1, double num2, Operation op) {
    switch (op) {
        case ADD:
            return num1 + num2;
        case SUBTRACT:
            return num1 - num2;
        case MULTIPLY:
            return num1 * num2;
        case DIVIDE:
            if (num2 != 0) // 防止除零错误
                return num1 / num2;
            else
                throw "Error: Division by zero is not allowed!";
        default:
            throw "Invalid operation"; // 如果输入了无效的运算符
    }
}

int main() {
    double num1, num2;
    cout << "Enter the first number: ";
    cin >> num1;
    cout << "Enter the second number: ";
    cin >> num2;
    cout << "Choose an operation (+, -, *, /): ";
    char choice;
    cin >> choice;
    
    Operation op;
    switch(choice) {
        case '+':
            op = ADD;
            break;
        case '-':
            op = SUBTRACT;
            break;
        case '*':
            op = MULTIPLY;
            break;
        case '/':
            op = DIVIDE;
            break;
        default:
            cout << "Invalid input! Please choose a valid operator." << endl;
            return 1; // 结束程序并返回错误码
    }

    try {
        double result = applyOperation(num1, num2, op);
        cout << "Result of the operation is: " << result << endl;
    } catch(const char* msg) {
        cerr << msg << endl;
    }

    return 0;
}