c++多态案例之计算器类

#include<iostream>
using namespace std;

//普通写法,如果想扩展，需要修改源码
//在实际开发中，提倡开闭原则，对扩展进行开发，对修改进行关闭
class Calculator {
public:
    int num1;
    int num2;
    int getResult(string oper) {
        if (oper == "+"){
            return num1 + num2;
        }
        else if (oper == "-") {
            return num1 - num2;
        }
        else if (oper == "*") {
            return num1 * num2;
        }
        else if (oper == "/") {
            return num1 / num2;
        }
        else
        {
            return -1;
        }
    }
};
//利用多态实现计算器
class AbstractCalculator {
public:
    int num1;
    int num2;
    virtual int getResult() {
        return 0;
    }
};
class Add :public AbstractCalculator {
    int getResult() {
        return num1 + num2;
    }
};
class Sub :public AbstractCalculator {
    int getResult() {
        return num1 - num2;
    }
};
class Mul :public AbstractCalculator {
    int getResult() {
        return num1 * num2;
    }
};
class Div :public AbstractCalculator {
    int getResult() {
        return num1 / num2;
    }
};
void test() {
    Calculator cal;
    cal.num1 = 6;
    cal.num2 = 3;
    int res = cal.getResult("/");
    cout<< res << endl;
}
void test2() {
    AbstractCalculator * cal = new Add;
    cal->num1 = 6;
    cal->num2 = 3;
    cout << "加法：" << cal->getResult() << endl;
    delete cal;
    cal = new Div;
    cal->num1 = 6;
    cal->num2 = 3;
    cout << "除法：" << cal->getResult() << endl;
    delete cal;
}

int main() {
    test2();
    system("pause");
    return 0;
}