php生成随机唯一邀请码/优惠码 固定长度UUID

function make_coupon_card() {        mt_srand((double)microtime()*10000);//optional for php 4.2.0 and up.        $charid = strtoupper(md5(uniqid(rand(), true)));        $hyphen = chr(45);// "-"        $uuid = //chr(123)// "{"                substr($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;            }