yyy.cpp

C++教程课件

#include <iostream.h>
class Alpha
{
  private:
    char* alpha_ptr;
  public:
    Alpha()			//构造函数不能是虚函数
    {
		    alpha_ptr = new char[5];
		 }	
    virtual void fn()=0;	//虚成员函数
     //virtual 
	 ~Alpha()		//虚析构函数
    {
		    delete[] alpha_ptr;
			cout<<"Calling Alpha's destructor!"<<endl;

		 }
};

class Beta: public Alpha
{
  private:
    char* ptrderived;
  public:
    Beta()
    {
		     ptrderived = new char[100];
		 }
    ~Beta()
    {
		   delete[] ptrderived;
           cout<<"Calling Beta's destructor!"<<endl;
		 }
		 void fn(){}
};
void main()
{
  Alpha *ptr = new Beta;
  delete ptr;
}