Pointers to Base and Derived classes
We can use pointers not only to the base objects but also to the objects of derived classes. Pointers to objects of a base class are type-compatible with pointers to objects of a derived class. Therefore, a single pointer variable can be made to point to objects belonging to different classes.
Consider the following declarations:
class Derived : public Base
{
// . . .
// . .
} ;
Base b ;
Base *ptr ;
Derived d ;
ptr = & b ;
ptr = & d ;
This is perfectly valid with C++ because d is an object derived from the class Base.
However, there is a problem in using ptr to access the public members of the derived class. Using ptr, we can access only those members inherited from base and not the members that originally belong to derived class. If a derived class member overrides a base class member, the pointer ignores the override.
