void Tree::add (int val)
    {
	binaryTreeNode *tmp;
	bool done = false;

	if (NULL == root)
	{
	    root = new binaryTreeNode (val);
	}
	else
	{
	    tmp = root;
	    while (!done)
	    {
		if (val < tmp->getValue ())
		{
		    if (NULL == tmp->getLeftChild ())
		    {
			tmp->setLeftChild (new binaryTreeNode (val));
			done = true;
		    }
		    else
		    {
			tmp = tmp->getLeftChild ();
		    }
		}
		else // the new value >= value at tmp
		{
		    if (NULL == tmp->getRightChild ())
		    {
			tmp->setRightChild (new binaryTreeNode (val));
			done = true;
		    }
		    else
		    {
			tmp = tmp->getRightChild ();
		    }
		}
	    }
	}
    }