Leitura XML em PHP

$filename ="/windows/discog/wwwroot/xml/questionario.xml";

$xml = simplexml_load_file($filename );

if (!$xml) {
$errors = libxml_get_errors();
foreach ($errors as $error) {
echo display_xml_error($error, $xml);
}
libxml_clear_errors();
}

var_dump($xml);
var_dump(get_object_vars($xml));

?>