项目1

#include <iostream>#include<Cmath>using namespace std;class Point{public:    Point():x(0),y(0){};    Point(double x0,double y0):x(x0),y(y0){};    void PrintPoint();    double x,y;};void Point::PrintPoint(){ cout<<"Point:("<<x<<","<<y<<")";}class Line:public Point{public:  Line(Point pts,Point pte):pts(pts),pte(pte){};  double Length();  void PrintLine();private: class Point pts,pte;};double Line::Length(){  return sqrt((pts.x-pte.x)*(pts.x-pte.x)+(pts.y-pte.y)*(pts.y-pte.y));}void Line::PrintLine(){cout<<"point message:"<<(pts.x+pte.x)/2<<"  "<<(pts.y+pts.y)/2<<endl;}int main(){  Point ps(-2,5),pe(7,9);  Line l(ps,pe);  cout<<"\n The Length of line  ";  cout<<l.Length()<<endl;  cout<<"\n The minddle point of Line";  l.PrintLine();}

运行结果：