第11周项目4-1点圆的关系

编号及代码：
/*
*Copyright(c)2015,烟台大学计算机与工程学院
*All rights reserved;
*文件名称：score.cpp
*作者：范星月
*完成日期：2015年5月27日
*版本号：v1.0
*
*问题描述：
*问题输入：先建立一个Point类，包含数据成员x,y;在以Point为基类，派生出Circle类，增加数据成员半径，基类的成员表示圆心，定义一个友元函数，判断点与圆的位置关系
*问题输出：
*/

#include <iostream>
#include<cmath>
using namespace std;
class Point
{
protected:
    double x,y;
public:
    Point (double a=0,double b=0):x(a),y(b){}
   double distance(Point &p);
    friend ostream&operator<<(ostream&output,Point &p);
};
double Point::distance(Point &p)
{
    return  sqrt((x-p.x)*(x-p.x)+(y-p.y)*(y-p.y));
}
ostream &operator<<(ostream&output,Point &p)
{
   output<<"("<<p.x<<","<<p.y<<")"<<endl;
    return output;
}
class Circle:public Point
{
protected:
    double r;
public:
    Circle(double a=0,double b=0,double r1=0):Point(a,b),r(r1){}

    friend ostream& operator<<(ostream &input,Circle &c);
   friend int locate(Point &p,Circle &c);

};

ostream& operator<<(ostream &output,Circle &c)
{
    output<<"Center=("<<c.x<<","<<c.y<<")"<<" r="<<c.r<<endl;
    return output;
}
int locate(Point &p,Circle &c)
{
    Point cp(c.x,c.y);
double     d=cp.distance(p);
    if (abs(d - c.r) < 1e-7)
        return 0;  //相等
    else if (d < c.r)
        return -1;  //圆内
    else
        return 1;  //圆外

}

int main()
{
    Circle  c1(3,2,4),c2(4,5,5);
    Point p1(1,1),p2(3,-2),p3(7,3);
    cout<<"c1:"<<c1;
    cout<<"p1:"<<p1;
    cout<<"点p1在圆c1之"<<((locate(p1,c1)>0)?"外":((locate(p1,c1)<0)?"内":"上"))<<endl;
    cout<<"p2:"<<p2;
    cout<<"点p2在圆c1之"<<((locate(p2,c1)>0)?"外":((locate(p2,c1)<0)?"内":"上"))<<endl;
    cout<<"p3:"<<p3;
    cout<<"点p3在圆c1之"<<((locate(p3,c1)>0)?"外":((locate(p3,c1)<0)?"内":"上"))<<endl;
}