Recursion and Objects

Anon

I've written this in JavaScript but now need it in PHP, the logic looks OK but the recursive function fails to call itself.

thanks

Andy

= CODE ====================================
<?php

/**
This is the main tree object.
*/
class DataTree {
var $label;
var $level;
var $children; // array

/**
Constructor
*/
function DataTree ($aLabel, $aLevel) {
	$this->label = $aLabel;
	$this->level = $aLevel;	
}

/**
*/
function addChild ($aNewChild) {
	$this->children[] = $aNewChild;
}

/**
Initial function to start the recursion from the top node.
*/
function toHTML () {
	$ls_HTML = $this->label."<br>";
	$ls_HTML .= $this->getNextLevel($this);

	// Finally return the HTML to be displayed.
	return $ls_HTML;		
}

/**
Recursive function called by each Node to display all of its children.
*/
function getNextLevel ($aNode) {
	$ls_show = "";

	$childCount = count(@$aNode->children);
	for ($j=0; $j < $childCount; $j++) {
		$child = $aNode->children[$j];

		$ls_show .= str_pad('', ($child->level*4), ' +--');
		$ls_show .= $child->label."<br>";

		// Here's the tricky bit. Take each child of the node and call this function again.
		$ls_show .= $aNode->getNextLevel($child);
	};

	return  $ls_show;		
}

}

/////////////////////////////////////////////////////////////////////

/**
Build the HTML
*/
echo "<BODY>";

$pr = new DataTree ('Root', 0);
$aaa = new DataTree ('AAA', 1);
$bbb = new DataTree ('BBB', 1);
$ccc = new DataTree ('CCC', 1);
$a1 = new DataTree ('A1', 2);
$b1 = new DataTree ('B1', 2);
$c1 = new DataTree ('C1', 2);

$pr->addChild($aaa);
$pr->addChild($bbb);
$pr->addChild($ccc);
$aaa->addChild($a1);
$bbb->addChild($b1);
$ccc->addChild($c1);

echo $pr->toHTML();

echo "</BODY>";

?>

Anon

Your getNextLevel function looks okay. I suspect the problem is the way you are adding objects to the tree.

You create $aaa, then you add $aaa to $pr, then you add $a1 to $aaa. I haven't tested it, but you probably added a copy of $aaa to $pr, then added $a1 to the original object instead of the copy that's stored in $pr($aaa instead of $pr->children[0]).