抽象接口的简单实现（纯虚类）

 纯虚函数 
#include "iostream.h"
class shape
{
public:
virtual  void draw()=0;
};

class circle:public shape
{
 void draw()
 {
  cout<<"draw"<<endl;
 }
};

shape* GetShape()
{
 return new circle;
}

void main()
{
 

 shape* pshape = GetShape();
 pshape->draw();
}