第十一周项目5.2类组的设计-优快云博客

本文介绍了一个使用C++实现的圆形类，该类继承自点类，并实现了设置和获取圆心坐标、设置半径、计算面积等功能。通过实例演示了圆形对象的创建和属性的修改。

/*
 *Copyright (c) 2015, 烟台大学计算机学院
 *All rights reserved.
 *文件名称：text.cpp
 *作者：陈栋梁
 *完成日期：2015年 5月 20日
 *版本号：v1.0
 *
 */
#include <iostream>
using namespace std;
class Point
{
public:
	Point(double x=0,double y=0);
	void setPoint(double,double);
	double getX( ) const {return x;}
	double getY( ) const {return y;}
	friend ostream & operator<<(ostream &,const Point &);
protected:
	double x,y;
};
Point::Point(double a,double b)
{
	x=a;
	y=b;
}
void Point::setPoint(double a,double b)
{
	x=a;
	y=b;
}

ostream & operator<<(ostream &output,const Point &p)
{
	output<<"["<<p.x<<","<<p.y<<"]"<<endl;
	return output;
}

class Circle:public Point
{
public:
	Circle(double x=0,double y=0,double r=0);
	void setRadius(double);
	double getRadius( ) const;
	double area ( ) const;
	friend ostream &operator<<(ostream &,const Circle &);
protected:
	double radius;
};
Circle::Circle(double a,double b,double r):Point(a,b),radius(r){ }
void Circle::setRadius(double r)
{
	radius=r;
}
double Circle::getRadius( ) const
{
	return radius;
}
double Circle::area( ) const
{
	return 3.14159*radius*radius;
}
ostream &operator<<(ostream &output,const Circle &c)
{
	output<<"Center=["<<c.x<<", "<<c.y<<"], r="<<c.radius<<", area="<<c.area( )<<endl;
	return output;
}

int main( )
{
	Circle c(3.5,6.4,5.2);
	cout<<"original circle:\nx="<<c.getX()<<", y="<<c.getY()<<", r="<<c.getRadius( ) <<", area="<<c.area( )<<endl;
	c.setPoint(5,5);
	cout<<"new circle:\n"<<c;
	return 0;
}

运行结果：