抽象类指针

#include<iostream>
using namespace std;

const double PI=3.14159;

class Shapes   //抽象类
{
protected:
    int x, y;
public:
    void setvalue(int d, int w=0){x=d;y=w;}
    virtual void disp()=0;//纯虚函数
};

class Square:public Shapes
{
public:
    void disp(){
        cout<<"矩形面积:"<<x*y<<endl;
    }
};

class Circle:public Shapes{
public:
    void disp(){
        cout<<"圆面积:"<<PI*x*x<<endl;
    }
};

int main()
{
    Shapes *ptr[2]; //定义对象指针数组
    Square s1;
    Circle c1;
    ptr[0] = &s1;
    ptr[0]->setvalue(10, 5);
    ptr[0]->disp();
    ptr[1] = &c1;
    ptr[1]->setvalue(10);
    ptr[1]->disp();
    return 0;

}