c++：多态

#include <iostream>

using namespace std;

class Shape
{
    protected:
            int weigth,heigth;
    public:
            Shape(int a = 0, int b = 0) //构造函数
            {
                weigth = a;
                heigth = b;
            }
            virtual int area() //虚函数
            {
                cout<<"parent class area :"<<endl;

                return 0;
            }
};

class Rec: public Shape{
    public:
            Rec(int a = 0,int b = 0) : Shape(a ,b) {}
            int area()
            {
                cout<<"Rec class area:"<<endl;
                return (weigth * heigth );
            }


};

class Tri : public Shape{
    public:
            Tri(int a = 0,int b = 0) : Shape(a,b) {}
            int area()
            {
                cout<< "tri class area"<<endl;
                return (weigth * heigth / 2);
            }
};

int main()
{
    Shape *shape;
    Rec rec(10,7);
    Tri tri(3,6);
    
    //存储矩形的面积
    shape = &rec;
    //求矩形的面积
    cout<<"rec area ="<<shape->area()<<endl;
    

    shape = &tri;
    cout<<"tri area ="<<shape->area()<<endl;
    return 0;

}

运行结果：

-VirtualBox:~/demo/c++/class$ ./duotai 
rec area =Rec class area:
70
tri area =tri class area
9