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Bug #49534 Incorrect dates returned with strtotime
Submitted: 2009-09-11 19:21 UTC Modified: 2009-09-11 19:39 UTC
From: re dot lewis at comcast dot net Assigned:
Status: Not a bug Package: Date/time related
PHP Version: 5.2.10 OS: Linux
Private report: No CVE-ID: None
 [2009-09-11 19:21 UTC] re dot lewis at comcast dot net
Description:
------------
On Sept 11, 2009 I was calculating the date for each successive sunday and used the code below, but after Nov 1, 2009, the day changes to Saturday.  Is this a bug?  It appears to be related to daylight savings time.

Reproduce code:
---------------
<?php
for ($w= 5; $w < 15; $w++) {
	echo date('Y-m-d, D, z', (strtotime('sunday') + $w*7*24*60*60)) . "<br>"; 
}
?>

Expected result:
----------------
Return the date of each sunday starting 5 weeks from this coming sunday.

Actual result:
--------------
2009-10-18, Sun, 290
2009-10-25, Sun, 297
2009-11-01, Sun, 304
2009-11-07, Sat, 310
2009-11-14, Sat, 317
2009-11-21, Sat, 324
2009-11-28, Sat, 331
2009-12-05, Sat, 338
2009-12-12, Sat, 345
2009-12-19, Sat, 352


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 [2009-09-11 19:27 UTC] rasmus@php.net
Which would be why it isn't a bug.  Start with a timestamp around noon to avoid DST issues like this.

You probably also want to use something like this instead:

$db = new DateTime('2008-12-31');
$de = new DateTime('2009-12-31');
$di = DateInterval::createFromDateString('Sunday next week');
$dp = new DatePeriod($db, $di, $de, DatePeriod::EXCLUDE_START_DATE);
foreach($dp as $dt) {
   echo $dt->format("F jS\n") . "<br>\n";
}

This would give you the date of each Sunday in 2009, except the first one (because of the EXCLUDE_START_DATE) option.

 [2009-09-11 19:39 UTC] re dot lewis at comcast dot net
Thanks for setting me straight.
 
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