専門家の方、返された XML の値を取得する方法を教えてください。

<?php<br />
header("Content-Type:text/html;   charset=utf-8");<br />
error_reporting(E_ALL ^ E_NOTICE);<br />
<br />
ob_start();<br />
require_once('lib/nusoap.php');<br />
<br />
$url ="http://wingcyx.gicp.net:1600/WeChatSrv.asmx?wsdl";<br />
$client = new nusoap_client($url, 'wsdl','','','','');<br />
$client->soap_defencoding='utf-8';<br />
$client->decode_utf8=false;<br />
$client->xml_encoding='utf-8';<br />
//参数转换为数组传递<br />
$ary = array('WeChat' => 'wingcyx', 'mobile' => '13670500598');<br />
$result = $client->call('regmember',$ary);<br />
<br />
//$result =get_object_vars($result);<br />
<br />
$doc = new DOMDocument();<br />
$doc->loadXML($result['regmemberResult']);<br />
echo $doc->getElementsByTagName('CardId')->item(0)->nodeValue;