学步园

#include<iostream>
#include<Cmath>
using namespace std;
class Point //定义坐标点类
{public:
	double x,y;   //点的横坐标和纵坐标
	Point(){x=0;y=0;}
	Point(double x0,double y0) {x=x0; y=y0;} 
	void PrintP(){cout<<"Point:("<<x<<","<<y<<")";}
};  
class Line: public Point   //利用坐标点类定义直线类, 其基类的数据成员表示直线的中点
{private:
	class Point pt1,pt2;   //直线的两个端点
public:
	Line(Point pts, Point pte);  //构造函数
	double Dx(){return pt2.x-pt1.x;}
	double Dy(){return pt2.y-pt1.y;}                                                          
	double Length();//计算直线的长度
	void PrintL();  //输出直线的两个端点和直线长度
};
//构造函数，分别用参数初始化对应的端点及由基类属性描述的中点
Line::Line(Point pts, Point pte):Point (((pts.x+pte.x)/2),((pts.y+pte.y)/2))
{      
    pt1=pts;      
    pt2=pte;      
    /*  if(pt1.x>pt2.x)   
    point((-Dx()/2),(-Dy()/2));   
    else   
    point((Dx()/2),(Dy()/2));*/      
}  
double Line::Length(){return sqrt(Dx()*Dx()+Dy()*Dy());}//计算直线的长度
void Line::PrintL()
{
	cout<<" 1st ";
	pt1.PrintP();
	cout<<"\n 2nd ";
	pt2.PrintP();
	cout<<"\n The middle point of Line: ";
	PrintP();
	cout<<"\n The Length of Line: "<<Length()<<endl;
}
int main()
{
	Point ps(-2,5),pe(7,9);
	Line l(ps,pe);
	l.PrintL();//输出直线l的信息
	l.PrintP();//输出直线l中点的信息
	cout<<endl;
	system("pause");
	return 0;
}

运行结果：

 1st Point:(-2,5)
 2nd Point:(7,9)
 The middle point of Line: Point:(2,7)
 The Length of Line: 9.84886
Point:(2,7)
请按任意键继续. . .