circle2.h.bak

用三个类来研究类的继承！类Point、Circle、Cylinder

//circle2.cpp
//类Circle的定义
#ifndef circle2_h
#define circle2_h

#include "point2.h"

class Circle: public Point{
	friend ostream &operator<< (ostream &output, const Circle &);
public:
	//默认构造函数
	Circle(float r=0, float x=0, float y=0);
	void setRadius(float);	//设置半径值
	float getRadius() const;	//返回半径值
	float area() const;	//计算圆的面积
protected:
	float radius;	//圆的半径
};

#endif