hmmmmmmm.........

An expression tree........

given: a/b + (c -d)c

Code:

                                                  +
                                                  /\ 
                                                 /  \ 
                                               '/'    \ 
                                               /\      \
                                              a  b     *
                                                       /  \
                                                      /    c
                                                     -
                                                    / \
                                                   c   d

what data members would the nodes contain? i'm a little lost. one node would contain a sign but it's direct children may contain a number or another sign, but it is unecessary to contain both.

struct node
{
char sign; //is this where i would use a union?
int value; //...or am i way of completely?
node *parent;
node *son; //son = child on "left" (conceptually)
node *daughter; //daughter child on "right"
}

> char sign; //is this where i would use a union?
> int value; //...or am i way of completely?
Looks like a good idea to me

So long as you have some reliable way of telling whether you should be looking at the sign or the value member of the union.

should trees always be grown from the root?

not all trees.. for example in a B-Tree a node is broken doen to form the new root.... But in the Binary tree the tree is grown from the root...

having a single string variable as the data member of the struct might be an alternative.

i want to write my own tree class....
which will look like this (stripped down for clearity)

Code:

template <class Object>
class TreeNode
{
	public:
	Object item;

	private:
	treenode *ptrBrother;  
	treenode *ptrSister;

};

template <class Object>
class BinaryTree
{
	private:
	TreeNode<Object> *ptrRoot;
};

The question is, in tree node, do you think
should just inherit type Object?

if so, would that look like this?

Code:

template<class Object> 
class TreeNode : public Object
{
	private:
	treenode *ptrBrother;  
	treenode *ptrSister;

};