Comment générer un fichier xml?

<?php 

$doc = new DOMdocument ('1.0','UTF-8');
$doc -> encoding ='UTF-8';
//sortie texte
$doc -> formatOutput = true
//parent
$root = $doc->createElement('page');
$root = $doc->appendChild($root);
//enfant
$title = $doc->createElement('titre');
$title=$root->appendChild($title);
//contenu de title
$text = $doc->createTextNode('ceci est du texte');
$text = $title->appendChild($text);

echo 'fini'. $doc->save("test.xml") . 'bytes';
?>