C/C++使用技巧1001例一书的配套代码

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