techInterview Discussion

How will you write your own dynamic cast which does the same
work as the dynamic cast which C++ provides.

class base {
  public :
    virtual der1* isDer1 () = 0 ;
    virtual der2* isDer2 () = 0 ;
};

class der1 : public base {
  public :
    der1* isDer1 () { return this; }
    der2* isDer2 () { return 0; }
};

class der2 : public base {
  public :
    der1* isDer1 () { return 0; }
    der2* isDer2 () { return this; }
};

Dynamica cast is for downcasting . I am not sure how Puneet's solution will work. I thought that something related to typeid would work.

Dyncamic cast will return NULL if I try to convert B* To D* if D is not derived from B.

Agree that typeid is probably the only reasonable way to do this.

D ; Can you give me an example to do that using typeid.

I thought typeid gave you access to the inheritance DAG, but it doesn't. You'd have to construct that out-of-band.

Can somebody come up with any kind of solution for this by writing a sample code