php怎么只获取访问页面的http状态码

<?php
     function GetHttpStatusCode($url){ 
         $curl = curl_init();
         curl_setopt($curl,CURLOPT_URL,$url);//获取内容url 
         curl_setopt($curl,CURLOPT_HEADER,1);//获取http头信息 
         curl_setopt($curl,CURLOPT_NOBODY,1);//不返回html的body信息 
         curl_setopt($curl,CURLOPT_RETURNTRANSFER,1);//返回数据流，不直接输出 
         curl_setopt($curl,CURLOPT_TIMEOUT,30); //超时时长，单位秒 
         curl_exec($curl);
         $rtn= curl_getinfo($curl,CURLINFO_HTTP_CODE);
         curl_close($curl);
         return  $rtn;
     }
     $url="http://www.biigroup.cn";
     echo GetHttpStatusCode($url);                                                                 ?>