如何使用diff在PHP中将天分成几周

Question

I am trying to group an index by weeks as opposed to days like the code currently does. My code for displaying the days since the start date (FIRST_DAY_STRING) and time on that day (TIME_SUFFIX) is below. I am having just a bit of trouble converting it to weeks since the start day instead of days.

Thanks for any help in advance. I would also appreciate an explanation of how to do it for months as well as I also need that.

<?php
define("FIRST_DAY_STRING", "2014-3-26");
define("SHIFT_DAYS", 'P2D');
define("TIME_SUFFIX", " 20:30:00 GMT+11:00");

$today = new DateTime();
$first_day = new DateTime(FIRST_DAY_STRING);
$interval = $first_day->diff($today);
$days = $interval->format('%R%a days');
$end_date = $today->add(new DateInterval(SHIFT_DAYS));

$day_number = intval($days) + 1;
$txid = "tx$day_number";
$end_time = $end_date->format('Y-n-j')
$end_time .= TIME_SUFFIX
?>

Answer 1

I did it myself. What I did was divide the inval($days) by 7 and rounded it to the nearest whole number:

$day_number = round(intval($days) / 7 + 1, 0);