php获取远程文件大小

/* **功能:获取远程文件的大小,返回值的单位是:字节 */ function get_fileSize($url){   if(!isset($url)||trim($url)==''){     return '';   }   ob_start();   $ch=curl_init($url);   curl_setopt($ch,CURLOPT_HEADER,1);   curl_setopt($ch,CURLOPT_NOBODY,1);   $okay=curl_exec($ch);   curl_close($ch);   $head=ob_get_contents();   ob_end_clean();   $regex='/Content-Length:/s([0-9].+?)/s/';   $count=preg_match($regex,$head,$matches);   return isset($matches[1])&&is_numeric($matches[1])?$matches[1]:''; }