大家好，Visual C 6.0中对像的定义如何理解？如  对像名.函数成员名  
具体的例子   如下的ptCenter.ShowPos()如何理解呢，请各们高手指教。
#include <iostream.h>
class CPoint
{
public:
   CPoint(int x,int y){
   nPosX=x;  nPosY=y;
   cout<<"CPoint类构造函数"《end1;
}
void ShowPos() {
  cout<<"当前位置：x="<<nPosX<<",y="<<nPosY<<end1;
}
Private
int nPosX,nPosY;
}

Class CRect
{
public:
CRect(int left,int top,int bottom,int right);
void Show() {
ptCenter.ShowPos();
}
private:
CPoint ptCenter;
}
CRect::CRect(int left,int top,int bottom,int right):size(right-left,bottom-top),ptCenter((left+right)/2,(top+bottom)/2
{}
void main()
{
CRect rc(10,120,70,230);
rc.Show();
}