不用指针只能调用基类

#include <iostream> using namespace std; class B { public: virtual void f() {cout<<"B::f"<<endl;} }; class D:public B { public: void f() {cout<<"D::f"<<endl;} }; void main() { B *pB=&d,&rB=d,b; D d; b=d; b.f(); pB->f(); rB.f(); }