inheritance & virtual functions

Hello,

I have an abstract base class called Node, which has got two derived classes, IntNode and StringNode.

class Node{ //abstract class
private:
Node* lnk;
public:
Node();
virtual ~Node();
void link(Node* n);
Node* link() const;
virtual void print()const=0;
};

class IntNode:public Node{
…//code here!
};

class StringNode:public Node{
…//code here!
};

My question is, when I write:
Node* myNode=new IntNode;

I do not have access to the member functions in class IntNode (they are declared as public), I have only access to the functions in the base class, but when I write:

IntNode* myNode= new IntNode;

I have access to all of the member functions, both base and derived.

What is really the difference between these two statements? And when should they be used? And what shall I do in order to be access the member functions?

Cheers!

Because node is a pointer to the base class, you can only access (with ->) the base functions.

If you only have a base pointer, then without casting you can only call base methods, regardless of the type of inheritence you're using. You'll either have to create an interface for all the derived functions in the base class (making them pure if necessary), cast (using dynamic_cast if you want to be safe), or re-design (templates ??).

If I wanted a parrot, I'll go to the pet shop! ;)