2012年 上半年 第十周 C++程序设计 （三十一）

【任务1】在下面一段类的定义中，需要填充的函数由注释内容给出了功能。#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)_________________(1)________________________ double Line::Length(){return __________(2)_____________};//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: "<<____(3)_____<<endl;}int main(){Point ps(-2,5),pe(7,9);Line l(ps,pe);____(4)_____//输出直线l的信息____(5)_____//输出直线l中点的信息system("pause");return 0;}

代码

 

#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) {pt1=pts;pt2=pte;x=Dx()/2;y=Dy()/2;}//计算直线的长度double Line::Length(){return sqrt((pt2.x-pt1.x)*(pt2.x-pt1.x)+(pt2.y-pt1.y)*(pt2.y-pt1.y));};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system("pause");return 0;}

运行结果

 

 1st Point:(-2,5) 2nd Point:(7,9) The middle point of Line: Point:(4.5,2) The Length of Line: 9.84886Point:(4.5,2)请按任意键继续. . .