请各位大神和高人为小弟指点迷津，帮忙分析一下以下代码的执行过程，小弟在编译器上把代码跑了一遍，但还是不太明白，希望得到您的详细解释。

#include <iostream>

using namespace std;

class Shape

{

public:     Shape(){}   

  virtual ~Shape() {}    

virtual float Area() const=0;   

  virtual Shape * Clone() const=0;

};

class Circle:public Shape

{

public:     Circle(float r):radius(r)      {}    

virtual ~Circle()              {}    

virtual float Area() const        

{ 

cout<<"Circle's Area ="<<radius*radius*3.1415926<<endl;          

   return radius*radius*3.1415926f;        

}  

 virtual Circle * Clone() const {return new Circle(*this); }

private:    

Circle(const Circle& rhs)       

  {             cout<<"Copy Construct Circle!"<<endl;          

   radius=rhs.radius;        

}

private:     float radius;

};

class Rectangle:public Shape

{

public:   

  Rectangle(float w,float h):width(w),height(h) {}    

virtual ~Rectangle()              {}   

  virtual float Area() const       

  {  cout<<"Rectangle's Area ="<<width*height<<endl;          

   return width*height;        

}    

virtual Rectangle * Clone() const

{return new Rectangle(*this); }

private:    

Rectangle(const Rectangle& rhs)       

  {  cout<<"Copy Construct Rectangle!"<<endl;             width=rhs.width;height=rhs.height;      

   }

private:   

  float width;  

float height;

};

int main(int argc, char* argv[])

{    

Shape * p1=new Circle(2.5);    

p1->Area();

 Shape * p2=new Rectangle(5,11);   

 p2->Area();

 Shape *p3=p1->Clone();  

 p3->Area();

 Shape *p4=p2->Clone();   

 p4->Area();

 delete p4;   

 delete p3;    

 delete p2;   

 delete p1;

 return 0;

}

对于您的热心解答，小弟不胜感激！