element.h

高等教育出版社出版的C++程序设计同步实验范例 希望对用这本教材得同学有点帮助

#include <math.h>
double const  PI=3.14159;
class CElement {
public:
    virtual void Show()=0;
	virtual double Area() = 0;
	CElement *Next;
};

class CPoint:public CElement{
friend class CLine;
protected:
	double x,y;
public:
	CPoint(){x = 0; y = 0; }
	CPoint(double xv,double yv){x = xv;y = yv;}
	double Area(){return 0;}
	void Show(){
		cout<<"x="<<x<<' '<<"y="<<y<<endl;
	}
};

class CCircle :public CPoint{
double radius;
public:
	CCircle(){ x = 0; y = 0; radius = 0; }
	CCircle(double xv,double yv,double vv):CPoint(xv,yv){
		radius = vv;
	}
	double Area(){
		return PI*radius*radius;
	}
void Show(){
		cout<<"x="<<x<<' '<<"y="<<y<<' '<<"radius="<<radius<<' '<<"Area="<<Area()<<endl;
	}
};

class CLine:public CElement{
		CPoint start,end;
	public:
		CLine():start(0,0),end(0,0){}
		CLine(double xv1,double yv1,double xv2,double yv2):
		start(xv1,yv1),end(xv2,yv2){ };
	double GetLength(){
		return sqrt((start.x-end.x)*(start.x-end.x)+(start.y-end.y)*(start.y-end.y));
	}
	double Area(){return 0;}
	void Show(){
		cout<<"start point:\n";
		start.Show();
		cout<<"end point:\n";
		end.Show();
		cout<<"Length="<<GetLength()<<endl;
	}
};

class CElemList{
protected:
	CElement *head;  			//  链表头指针定义为基类类型
public:
	CElemList():head(NULL){}
	~CElemList();
	void Insert(CElement *);    	//  插入元素
	int Delete(CElement *);		//  删除元素
	void Show();					//  显示所有元素
	CElement* GetHead(){ return head; }		//  取得链表头
};