c++.txt

C++课程实验源程序代码：继承与派生。用VC++环境编写。

继承与派生



#include <iostream>
#include <cmath>
using namespace std;
#define PI  3.14159
class point{
      friend class line;
protected:
	double x,y;
public:
	point(){x=0;y=0;}
	point(double xv,double yv){x=xv;y=yv;}
	double area(){return 0;}
	void show(){cout<<"x="<<x<<"y="<<y<<endl;}
};
class circle:public point
{
  double radius;
public:
	circle(){x=0;y=0;radius=0;}
	circle(double xv,double yv,double vv):point(xv,vv)
	{
		radius=vv;
	}
	circle(circle &cir):point(cir)
	{
	  radius=cir.radius;
	}
	circle & operator=(circle &cir)
	{
		this->point::operator=(cir);
		radius=cir.radius;
		return *this;
	}
	double area()
	{
	return PI*radius*radius;
	}
	void show()
	{
	cout<<"x="<<x<<"y="<<y<<"radius="<<radius<<endl;
	}
};
class line{
   point start,end;
public:
	line():start(0,0),end(0,0){}
	line(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();
	}
};
int main()
{
point pt(0,0);
circle cl1(100,100,10),cl2(cl1),cl3;
line ln1(0,0,100,100);
cout<<"tht area is:"<<pt.area()<<endl;
pt.show();
cout<<"cl1 area :"<<cl1.area()<<endl;
cl1.show();
cout<<"cl1 area:"<<cl2.area()<<endl;
cl2.show();
cl3=cl1;
cout<<"cl3 area :"<<cl3.area()<<endl;
cl3.show();
cout<<"线面积"<<ln1.area()<<'\t'<<"线长度"<<ln1.getlength()<<endl;
ln1.show();
return 0;
}