Wie kann ich ein mehrdimensionales PHP-Array effizient in ein SimpleXML-Objekt konvertieren?

function array_to_xml( $data, &$xml_data ) {
    foreach( $data as $key => $value ) {
        if( is_array($value) ) {
            if( is_numeric($key) ){
                $key = 'item'.$key; //dealing with <0/>..<n/> issues
            }
            $subnode = $xml_data->addChild($key);
            array_to_xml($value, $subnode);
        } else {
            $xml_data->addChild("$key",htmlspecialchars("$value"));
        }
     }
}

$data = array('total_stud' => 500,
    'student' => array(
        0 => array(
            'id' => 1,
            'name' => 'abc',
            'address' => array(
                'city' => 'Pune',
                'zip' => '411006'
            )
        ),
        1 => array(
            'id' => 2,
            'name' => 'xyz',
            'address' => array(
                'city' => 'Mumbai',
                'zip' => '400906'
            )
        )
    )
);

$xml_data = new SimpleXMLElement('<?xml version="1.0"?><student_info></student_info>');

array_to_xml($data, $xml_data);

<?xml version="1.0"?>
<student_info>
    <total_stud>500</total_stud>
    <student>
        <id>1</id>
        <name>abc</name>
        <address>
            <city>Pune</city>
            <zip>411006</zip>
        </address>
    </student>
    <student>
        <id>1</id>
        <name>abc</name>
        <address>
            <city>Mumbai</city>
            <zip>400906</zip>
        </address>
    </student>
</student_info>