PHP array to xml

<?php
#echo strtotime('2013-10-27 19:30:00');


$arr = array();

$arr['news'] = array(
array('nid' => 1, 'title' => 'test'),
array('nid' => 2, 'title' => 'test'),
);

$arr['news2'] = array(
array('nid' => 3, 'title' => 'test'),
array('nid' => 4, 'title' => 'test'),
);

try
{
$xml = new array2xml('root');
$xml->createNode( $arr );
echo $xml;
}
catch (Exception $e)
{
echo $e->getMessage();
}

/**
*
* Array 2 XML class
* Convert an array or multi-dimentional array to XML
*
* @author Kevin Waterson
* @copyright 2009 PHPRO.ORG
*
*/
class array2xml extends DomDocument
{

public $nodeName;

private $xpath;

private $root;

private $node_name;


/**
* Constructor, duh
*
* Set up the DOM environment
*
* @param string $root The name of the root node
* @param string $nod_name The name numeric keys are called
*
*/
public function __construct($root='root', $node_name='node')
{
parent::__construct();

/*** set the encoding ***/
$this->encoding = "utf-8";

/*** format the output ***/
$this->formatOutput = true;

/*** set the node names ***/
$this->node_name = $node_name;

/*** create the root element ***/
$this->root = $this->appendChild($this->createElement( $root ));

$this->xpath = new DomXPath($this);
}

/*
* creates the XML representation of the array
*
* @access public
* @param array $arr The array to convert
* @aparam string $node The name given to child nodes when recursing
*
*/
public function createNode( $arr, $node = null)
{
if (is_null($node))
{
$node = $this->root;
}
foreach($arr as $element => $value)
{
$element = is_numeric( $element ) ? $this->node_name : $element;

$child = $this->createElement($element, (is_array($value) ? null : $value));
$node->appendChild($child);

if (is_array($value))
{
self::createNode($value, $child);
}
}
}
/*
* Return the generated XML as a string
*
* @access public
* @return string
*
*/
public function __toString()
{
return $this->saveXML();
}

/*
* array2xml::query() - perform an XPath query on the XML representation of the array
* @param str $query - query to perform
* @return mixed
*/
public function query($query)
{
return $this->xpath->evaluate($query);
}

} // end of class