填空题

以下程序的执行结果为【 】。   #include<iostream>   using namespace std;   class base   {    public:     virtual void who( )    {     cout < < "base class" < <end1;    };    class derivel:public base    {     public:      void who( )     {      cout < <"derivel class" < <end1;     };     }    class derive2:public base     {      public:       void who( )      {       cout< <"derive2 class"< <end1;      }     };     void main( )     {      base obj1,* p;      derivel obi2;      derive2 obj3;      p=&obj1;      p->who( );      p=&obj2;      p->who( );      p=&obj3;      p->who( );     }

【参考答案】

base class derivel class derive2 class