题解 | #多态实现计算器功能#

#include <iostream>
using namespace std;

class BaseCalculator {
    public:
        int m_A;
        int m_B;
        // write your code here......
        virtual int getResult(){//这里的函数必须虚化，不然后面的程序可能会读到这里
            return 0;//这里随便取，因为已经虚化
        }
};

// 加法计算器类
class AddCalculator : public BaseCalculator {
    // write your code here......
    public:
        int getResult(){
            return m_A+m_B;//返回加法
        }
};

// 减法计算器类
class SubCalculator : public BaseCalculator {
    // write your code here......
    public:
        int getResult(){
            return m_A-m_B;//返回减法
        }
};


int main() {

    BaseCalculator* cal = new AddCalculator;//从AddCalculator堆里开出内存，储存cal
    cal->m_A = 10;
    cal->m_B = 20;
    cout << cal->getResult() << endl;
    delete cal;//删除这个内存

    cal = new SubCalculator;
    cal->m_A = 20;
    cal->m_B = 10;
    cout << cal->getResult() << endl;
    delete cal;

    return 0;
}