服务端生成券码

 public function get_voucher_code($member_id = 0){
        static $num = 1;
        $sign_arr = array();
        $sign_arr[] = sprintf('%02d',mt_rand(10,99));
        $sign_arr[] = sprintf('%03d', (float) microtime() * 1000);
        $sign_arr[] = sprintf('%010d',time() - 946656000);
        if($member_id){
            $sign_arr[] = sprintf('%03d', (int) $member_id % 1000);
        } else {
            //自增变量
            $tmpnum = 0;
            if ($num > 99){
                $tmpnum = substr($num, -1, 2);
            } else {
                $tmpnum = $num;
            }
            $sign_arr[] = sprintf('%02d',$tmpnum);
            $sign_arr[] = mt_rand(1,9);
        }
        $code = implode('',$sign_arr);
        $num += 1;
        return $code;
    }