PHP生成 uuid

//  生成UUID，并去掉分割符

function guid() {

    if (function_exists('com_create_guid')){

        $uuid = com_create_guid();

    }else{

        mt_srand((double)microtime()*);//optional for php 4.2.0 and up.

        $charid = strtoupper(md5(uniqid(rand(), true)));

        $hyphen = chr();// "-"

        $uuid = chr()// "{"

                .substr($charid, , ).$hyphen

                .substr($charid, , ).$hyphen

                .substr($charid,, ).$hyphen

                .substr($charid,, ).$hyphen

                .substr($charid,,)

                .chr();// "}"

    }

    $uuid = str_replace(array('-', '{', '}'), '', $uuid);

    return $uuid;

}