php获取远程文件的大小

/*
**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]:'';
}