php – 确定一周是奇数还是偶数

其目的是允许某人选择运送产品的交货频率.如果有人想要他们的产品每隔一周,系统需要确定他们是否应该在下周或两周后获得订单.我们称之为一周或B周.

请记住,我没有写这个,我只是想弄清楚它,并希望有一些帮助评估其准确性：

if (date("l") == "Monday" ) {
            $start = 0;
        } else if (date("l") == "Tuesday" || date("l") == "Wednesday" || date("l") == "Thursday" || date("l") == "Friday" || date("l") == "Saturday"|| date("l") == "Sunday") {
        $start = -1;
    }

    // if changing to every other week set to next week's a/b-ness
    $a_week_tid = 34;
    $b_week_tid = 35;

    $every_other_week_frequency_id = 32;

    if ($delivery_frequency == $every_other_week_frequency_id) {
        $julian = (int) (strtotime('Monday +' . $start . ' week') / 86400);
        $julian_week = ($julian-4) / 7;
        if ($julian_week % 2) {
            $today_a_or_b = $b_week_tid;
            $next_week_a_or_b = $a_week_tid;
            $a_or_b_week_string = '(A Week)';
        } else {
            $today_a_or_b = $a_week_tid;
            $next_week_a_or_b = $b_week_tid;
            $a_or_b_week_string = '(B Week)';
        }
    } else {
        $next_week_a_or_b = NULL;
        $a_or_b_week_string = NULL;
    }

此代码未被注释或记录.令我困惑的部分是：

>为什么4从朱利安减去,然后除以7？
>如果今天是星期一,$julian_week是2129,而2129％2评估为TRUE.那是对的吗？
>这甚至应该怎么做？我不能用日期(‘w’)重写这个更容易吗？