exam2_2.cpp

C++程序设计源代码例

#include "iostream.h"
class Point    //　定义基类
{	int  m_x,  m_y;	
 public:			
	Point(int x,int y){ m_x=x; m_y=y;  }	
	int get_x(){ return m_x; }	
	int get_y() { return m_y;}
};

class Circle : public Point   //定义派生类，公有继承
{ 
	double  radius;	
public:			
	Circle(int x,int y,double r) : Point(x,y)//派生类没有继承基类的构造函数，而是通过	
	{ radius=r;}                             //访问基类的构造函数初始化基类的数据成员
	double Area(void) {return 3.14*radius*radius; }  //计算圆面积			
	int get_centreX() {return get_x();}  //调用基类中的成员函数访问基类数据，获得	
	int get_centreY() {return get_y();}  //圆心坐标
};

void main()
{
	int x,y;
	double r;
	cout<<"x="; 
	cin>>x;
	cout<<"y="; 
	cin>>y;
	cout<<"r="; 
	cin>>r;
	Circle c(x,y,r);
	cout<<"the centre of the Circle is "<<c.get_centreX()<<" and "<<c.get_centreY()<<endl;
	cout<<"the Area of the Circle is "<<c.Area()<<endl;
}