OOP: Turning a tree of nodes

[Anon]

I'm trying to build a node tree structure of objects with pointers to other objects (parent nodes having pointers to all its children). The input I get is from a mysql database, where each entry has the id of its parent node. So in a way, what I want is to turn the tree around. The code I have is similar to this:

class Node {
var $id;
var $children;

function AddReply($child) {
$this->children[$child->id] = $child;
}
}

Somehow, the update only seems to work for the root node. All the children of all other nodes are lost. And lost, alas, so am I. Could it be that I am unable to update the children-array because there is another pointer pointing to the object I'm accessing?

[daarius]

function AddReply($child) {
$this->children[$child->id] = $child;
}

whats the $child->id ??

shouldnt it be: $this->id ?
and if you are using $child which is passed from function as a class name, then where is that class initialised?.

[Anon]

Thanks for the reply. I'll try to explain a bit further:

$child is a reference to another node, which has its own $id, hence $child->id. The parent node is supposed to keep track of its children by means of an associative array called children. The child object is created "outside" the class. Since the child knows the id of its parent, I can easily obtain a pointer to the parent object as well. I then call the function (which should be called AddChild, not AddReply) for the parent like this (outside the class):

$parent->AddChild($child);

Somehow, though, I am unable to update the parent's array of children for any other node than the root... now why on earth is that? :-)