Question

I’m writing a php script that iterates over the Monday of each week.

However the script seemed to get out of sync after 22nd of October.

<?php

$october_8th = strtotime("2012-10-08");

$one_week = 7 * 24 * 60 * 60;

$october_15th = $october_8th + $one_week;
$october_22nd = $october_15th + $one_week;
$october_29th = $october_22nd + $one_week;
$november_5th = $october_29th + $one_week;

echo date("Y-m-d -> l", $october_8th) . '<br />';
echo date("Y-m-d -> l", $october_15th) . '<br />';
echo date("Y-m-d -> l", $october_22nd) . '<br />';
echo date("Y-m-d -> l", $october_29th) . '<br />';
echo date("Y-m-d -> l", $november_5th) . '<br />';

This would output:

2012-10-08 -> Monday
2012-10-15 -> Monday
2012-10-22 -> Monday
2012-10-28 -> Sunday
2012-11-04 -> Sunday

I would expect it to say the 29th of October but it gets stuck at the 28th.

How should I get around this problem?

Answer 1

A preferred choice would be to use PHP’s date-related classes to get the dates.

These classes importantly handle the daylight-savings boundaries for you, in a way that manually adding a given number of seconds to a Unix timestamp (the number from strtotime() that you used) cannot.

The following example takes your start dates and loops four times, each time adding a week to the date.

$start_date  = new DateTime('2012-10-08');
$interval    = new DateInterval('P1W');
$recurrences = 4;

foreach (new DatePeriod($start_date, $interval, $recurrences) as $date) {
    echo $date->format('Y-m-d -> l') . '<br/>';
}

PHP Manual links:

• The DatePeriod class
• The DateInterval class
• The DateTime class