按教程上的写了个类组合小程序，在编译的时候通不过了，请教各位，是哪里错了呢？要怎么改？
程序如下：

#include<iostream>
#include<math.h>
using namespace std;

class Poing
{private:
float x,y;//点的坐标
public:
Point(float xx,float yy)
{cout<<"point构造函数"<<endl;
x=xx;y=yy;
}
Point(Point &p)
{x=p.x;y=p.y;
cout<<"Point拷贝构造函数"<<endl;
}
float GetX(void){return x;}
float GetY(void){return y;}
};

class Distance
{
private:
Point p1,p2;
double dist;
public:
Distance(Point a,Point b);
double GetDis(void){return dist;};
}
Distance::Distance(Point a,Point b):p1(a),p2(b)
{cout<<"Distance构造函数"<<endl;
double x=double(p1.GetX()-p2.GetX());
double y=double(p1.GetY()-p2.GetY());
dist=sqrt(x*x+y*y);
}
void main()
{
Point myp1(1,1),myp2(4,5);
Distance myd(myp1,myp2);
cout<<"the distance is:";
cout<<myd.GetDis()<<endl;
}

就是这个小程序啦：)
会的朋友一定帮忙哟，请你喝酒

貌似友元函数的问题。。。还无解，高手来赐教。。。

#include<iostream>
#include<math.h>
using namespace std;

class Point
{
private:
float x,y;//点的坐标
public:
Point(float xx,float yy)
{
cout<<"point构造函数"<<endl;
x=xx;y=yy;
}
Point(const Point &p);

float GetX(void){return x;}
float GetY(void){return y;}
};

Point::Point(const Point &p)
{x=p.x;y=p.y;
cout<<"Point拷贝构造函数"<<endl;
}

class Distance
{
private:
Point p1,p2;
double dist;
public:
Distance(Point a,Point b);
double GetDis(void){return dist;};
};
Distance::Distance(Point a,Point b):p1(a),p2(b)
{
cout<<"Distance构造函数"<<endl;
double x=double(p1.GetX()-p2.GetX());
double y=double(p1.GetY()-p2.GetY());
dist=sqrt(x*x+y*y);
}

void main()
{
Point myp1(1,1),myp2(4,5);
Distance myd(myp1,myp2);
cout<<"the distance is:";
cout<<myd.GetDis()<<endl;
}

#include<iostream>
#include<math.h>
using namespace std;

class Poing
{private:
float x,y;//点的坐标
public:
Point(float xx,float yy)
{cout<<"point构造函数"<<endl;
x=xx;y=yy;
}
Point(Point &p)
{x=p.x;y=p.y;
cout<<"Point拷贝构造函数"<<endl; //拷贝构造建议你写在外面...
}
float GetX(void){return x;}
float GetY(void){return y;}
};

class Distance
{
private:
Point p1,p2;
double dist;
public:
Distance(Point a,Point b);
double GetDis(void){return dist;};
}; //少了个分号..
Distance::Distance(Point a,Point b):p1(a),p2(b)
{cout<<"Distance构造函数"<<endl;
double x=double(p1.GetX()-p2.GetX());
double y=double(p1.GetY()-p2.GetY());
dist=sqrt(x*x+y*y);
}
void main()
{
Point myp1(1,1),myp2(4,5);
Distance myd(myp1,myp2);
cout<<"the distance is:";
cout<<myd.GetDis()<<endl;
}

谢谢楼上的朋友，现存编译是通过了，可是又连接不上呢呀。下面是提示
Linking...
LIBCD.lib(wincrt0.obj) : error LNK2001: unresolved external symbol _WinMain@16
Debug/111.exe : fatal error LNK1120: 1 unresolved externals
执行 link.exe 时出错.

111.exe - 1 error(s), 0 warning(s)