c++,Calculator类为抽象类

要求：
（1）已知Calculator类为抽象类，包含两个protected的double类型变量 x与y；
（2）Add类与Mul类均从Calculator类公有派生，分别使用result()函数进行加与乘的运算；
请根据运行结果与main函数将程序补充完整。
请注意第2个操作数为负时的输出形式。
例1（只有第1行为输入）：
2.2 3.33
2.2+3.33=5.53
3.33*2.2=7.326

例2（只有第1行为输入）：
-2.2 -3.3
-2.2-3.3=-5.5
-3.3*(-2.2)=7.26

请注意，main()函数（或函数调用）必须按如下所示编写：
int main()
{
Calculator *pc;
double x,y;
cin>>x>>y;
Add a1(x,y);
Mul m1(x,y);
pc=&a1;
pc->result();
pc=&m1;
pc->result();
return 0;
}

参考一下

#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
#include<string>
using namespace std;
 
//普通写法
class calculator
{
public:
 
    int getResult(string oper)
    {
        if (oper == "+")
        {
            return m_Num1 + m_Num2;
        }
        else if (oper == "-")
        {
            return m_Num1 - m_Num2;
        }
        else if (oper == "*")
        {
            return m_Num1 * m_Num2;
        }
        else if (oper == "/")
        {
            return m_Num1 / m_Num2;
        }
    }
 
    int m_Num1;
    int m_Num2;
};
void test()
{
    calculator c;
    c.m_Num1 = 100;
    c.m_Num2 = 10;
 
    cout << c.m_Num1 << "+" << c.m_Num2 << "=" << c.getResult("+") << endl;
    cout << c.m_Num1 << "-" << c.m_Num2 << "=" << c.getResult("-") << endl;
    cout << c.m_Num1 << "*" << c.m_Num2 << "=" << c.getResult("*") << endl;
    cout << c.m_Num1 << "/" << c.m_Num2 << "=" << c.getResult("/") << endl;
}
int main()
{
 
    test();
 
    system("pause");
    return 0;
}