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;
        
    }