class A{
public:
    virtual void RunA()=0;
};
class B{
public:
    virtual void RunB()=0;
};
class C: public A, public B{
public:
    virtual void RunA(){ printf("RunA\n"); }
    virtual void RunB(){ printf("RunB\n"); }
};

int _tmain(int argc, _TCHAR* argv[])
{
    C c;
    A* pa = &c;
    pa->RunA();

    B* pb = (B*)pa;    
    pb->RunB();        // error! Call RunA instead RunB !
    B* pb1 = (B*)(C*) pa;    // pb1 != pb
    pb1->RunB();        // good!

    return 0;
}