项目2.

#include <iostream>#include <cmath>using namespace std;class CPoint  {private:      double x;  // 横坐标      double y;  // 纵坐标   public:     CPoint(double xx=0,double yy=0):x(xx),y(yy){}     double distance1(CPoint &); //成员函数的声明、    friend double distance2(CPoint &,CPoint &); double getx(){return x;}double gety(){return y;}};double distance3(CPoint &,CPoint &);  //一般函数声明double CPoint::distance1(CPoint &p)  {return (sqrt((x-p.x)*(x-p.x)+(y-p.y)*(y-p.y)));}double distance2(CPoint &p1,CPoint &p2){double x=p1.x-p2.x;double y=p1.y-p2.y;return (sqrt((x*x)+(y*y)));}double distance3(CPoint &p1,CPoint &p2){  double x=p1.getx()-p2.getx();  double y=p1.gety()-p2.gety();  return (sqrt((x*x)+(y*y)));}int main(){CPoint p1(1,1), p2(0,0);      cout<<p1.distance1(p2)<<endl;      cout<<distance2(p1,p2)<<endl;      cout<<distance3(p1,p2)<<endl;      system("pause");      return 0; }