c++ defining a Node class, which has a private variable of Node (a Node for use in a*)

Question

I am very new to c++ and i am trying to define a Node class which holds information about another node, in this case the node will be the parent node so i can trace the most optimal route using an A* search.

so far i have tried (node.h file):

class node{

    private:
    int xCoord;
    int yCoord;
    int value;
    int hueristicCost;
    int pathCost;
    class node parent;

    public:
    node(int xC, int yC, int value);
    int getXPos();
    int getYPos();
    int getValue();


};

But this throws the compilation error:

node.h:10:13: error: field ‘parent’ has incomplete type

I am probably missing something stupidly obvious, but how would i go about completing this?

Answer 1

A member must be a complete type (as the error message oblivious already tells you). This means that you can´t have a forward declared member.

Notice, that you can already use node (as complete type) inside the node class.

However, defining a member of type node is still not possible, because this would lead to infinit recursion. Thus you probably want a node* if you have a tree-like model. Also notice that class Foo* member; is indeed possible. This is the usual solution if you really cant avoid forward declaration.

Answer 2

You can't declare an object of a class inside that class.

Possible duplicate: why can't we declare object of a class inside the same class?

Instead, you can define a pointer as others have mentioned:

node* parent

Answer 3

class node parent;

should be:

node parent;

or rather:

node* parent;