返回2个时间戳的倒计时

    function timediff($begin_time, $end_time)
    {
        $second = $end_time - $begin_time; //结束时间戳减去当前时间戳
        // echo $second;
        $day = floor($second / 3600 / 24);    //倒计时还有多少天
        $hr = floor($second / 3600 % 24);     //倒计时还有多少小时（%取余数）
        $min = floor($second / 60 % 60);      //倒计时还有多少分钟
        $sec = floor($second % 60);         //倒计时还有多少秒
        if (strlen($hr) == 1) {
            $hr = "0" . $hr;
        }
        if (strlen($min) == 1) {
            $min = "0" . $min;
        }
        if (strlen($sec) == 1) {
            $sec = "0" . $sec;
        }
        $str = $hr . ":" . $min . ":" . $sec . ":";  //组合成字符串
        return $str;
    }