定义一个Point类，派生出Circle类，计算各派生类对象的面积Area（）

定义一个Point类，派生出Circle类，计算各派生类对象的面积Area（）

#include<iostream>    
using namespace std;     
class Point    
{ 
	protected:  
    int x,y;    
    
    public:    
     Point(){}  
     int GetX() {cin>>x;}     
     int GetY() {cin>>y;}     
};     
class Circle:public Point    
{    
    int r;  
    public:    
    Circle():Point(){}  
    int GetR(){cin>>r;}  
    float Area() {return 3.14*r*r;}  
    void show()  
    {
		cout << "circle area : " <<Area()<<endl;
	}  
      
};     
    
int main()    
{  
	Circle c1;  
	c1.GetX();  
	c1.GetY();  
	c1.GetR();  
	c1.show();  
	return 0;  
}