这是《C／C++程序员实用大全》上面的源码

				#include 
				
				class Base 
				{
				 public:
				   void base_message(void) { cout 				};
				
				class Derived: public Base 
				{
				 public:
				   void derived_message(void) { cout 				};
				
				void main(void)
				 {
				   Base *base_pointer = new Base;
				   base_pointer->base_message();
				   
				   base_pointer = new Derived;
				   base_pointer->base_message();
				 }