rectangle.h

在考虑平面上“点类”和“矩形类”的关系时

class Point
{
public:
	Point(float xx=0,float yy=0)
	{x=xx;y=yy;}
	Point(Point &p){x=p.x;y=p.y;}
	~Point(){};
	float Getx(){return x;}
	float Gety(){return y;}
	void SetP(float xx=0,float yy=0){x=xx;y=yy;}
	void Move(float xoff,float yoff){x+=xoff;y+=yoff;}
private:
	float x,y;};
	
	class Rectangle:public Point
	{
	public:
		void Set(float xx,float yy,float w,float h)
		{
		SetP(xx,yy);  W=w;  H=h;
		}
	
		float GetH(){return H;}
		float GetW(){return W;}
		float Area()
		{return W*H;}
		float Cum()
		{return 2*(W+H);}
	private:
	  float	W,H;};