C++深入理解虚函数

转载链接

补充代码：

#include<iostream>
using namespace std;


class Shape//形状类
{
public:
     virtual double calcArea()
    {
        cout << "calcArea" << endl;
        return 0;
    }
};
class Circle:public Shape      //公有继承自形状类的圆形类
{
public:
    Circle(double r) :m_dR(r){}
    double calcArea();
private:
    double m_dR;
};
double Circle::calcArea()
{
    return 3.14*m_dR*m_dR;
}
class Rect :public Shape       //公有继承自形状类的矩形类
{
public:
    Rect(double width, double height) :m_dHeight(width), m_dWidth(height){}
    double calcArea();
private:
    double m_dWidth;
    double m_dHeight;
};
double Rect::calcArea()
{
    return m_dWidth*m_dHeight;
}
int main()
{
    /*基类指针指向派生类对象的方式*/
    Shape *shape1 = new Circle(4.0);
    Shape *shape2 = new Rect(3.0, 5.0);
    
    cout<<"area="<<shape1->calcArea();
    cout<<"area="<<shape2->calcArea();
    /*基类对象引用绑定到派生类对象上的方式*/
    /*Rect rct(3.0, 5.0);
    Shape &r = rct;
    cout << "area=" << r.calcArea();*/
    system("pause");
    return 0;
}