php生成uuid 工具方法

/**
* 生成uuid
* @copyright [chenghuan]
* @license   [license]
* @version   [version]
* @return    [string]      [uuid] 长度36
*/
function guid(){
$uuid = '';
if (function_exists('com_create_guid')){
return com_create_guid();
}else{
mt_srand((double)microtime()*10000);//optional for php 4.2.0 and up.
$charid = strtoupper(md5(uniqid(rand(), true)));
$hyphen = chr(45);// "-"
//$uuid = //chr(123)// "{"
$uuid .= substr($charid, 0, 8).$hyphen
.substr($charid, 8, 4).$hyphen
.substr($charid,12, 4).$hyphen
.substr($charid,16, 4).$hyphen
.substr($charid,20,12);
//.chr(125);// "}"
return $uuid;
}
}