#include＜iostream＞
using namespace std;
class B
{public:
～B 1{cout＜＜"B construct"＜＜endl;}
virtual void f 2=0;
};
class Dev: public B
{public:
～Dev 3{cout＜＜"B construct"＜＜endl;}
virtual void f 4{cout＜＜"Dev::f"＜＜endl;}
};
void main 5
{ B*=a=new B 6;
Dev p;
a =&p;
a-＞f 7;
}