#include <iostream>

using namespace std;

class B{
public:
    virtual void call() { cout<<"Bn"; };
};

class D: public B{
public:
    void call()  {  cout<<"Dn"; }
};

int _tmain(int argc, _TCHAR* argv[])
{
    B b;
    D d;

    b.call(); // output is "B"

    d.call(); // output is "D"

    B* obj = &d;
    obj->call(); // output is "D"

    return 0;
}

Base * obj = &DerivedA;