有如下程序:
#include<iostream>
using namespace std;
class B
public:
virtual void show( )cout<<"B";
;
class D:public B
public:
void show( )cout<<"D";
;
void funl(B*ptr)ptr->show( );
void fun2(B&ref);ref.show( );
void fun3(B b)b.show( );
int nlain( )
B b,*P=Dew D;
D d;
funl(p);
fun2(b);
fun3(d);
return 0;
程序的输出结果是
A.BBB
B.BBD
C.DBB
D.DBD