请用c++写一个简易计算器

当然可以，下面是一个简单的C++控制台版四则运算计算器的示例：

#include <iostream>
using namespace std;

int add(int a, int b) {
    return a + b;
}

int subtract(int a, int b) {
    return a - b;
}

int multiply(int a, int b) {
    return a * b;
}

int divide(int a, int b) {
    if (b != 0)
        return a / b;
    else
        throw "Error: Division by zero is not allowed!";
}

int main() {
    cout << "Welcome to Simple Calculator!" << endl;
    int num1, num2;
    char operation;

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

    switch(operation) {
        case '+':
            cout << "Result: " << add(num1, num2) << endl;
            break;
        case '-':
            cout << "Result: " << subtract(num1, num2) << endl;
            break;
        case '*':
            cout << "Result: " << multiply(num1, num2) << endl;
            break;
        case '/':
            cout << "Result: " << divide(num1, num2) << endl;
            break;
        default:
            cout << "Invalid operator! Please use +, -, *, or /." << endl;
            break;
    }

    return 0;
}

在这个例子中，我们定义了四个函数分别对应加、减、乘、除操作，并在`main`函数中根据用户输入的运算符选择相应的函数进行计算。