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Bug #27780 strtotime does not respect DST
Submitted: 2004-03-30 10:52 UTC Modified: 2005-10-21 11:37 UTC
From: Hua dot Qu at volvo dot com Assigned: derick (profile)
Status: Closed Package: Date/time related
PHP Version: 5.1.0RC3, 4.3.11 OS: Windows 2000, Cygwin
Private report: No CVE-ID: None
 [2004-03-30 10:52 UTC] Hua dot Qu at volvo dot com
strtotime($tm + 1 xxx) always adds one more hour to the result, if the result-time is in the summertime, no matter $tm is in the summertime or not.

It is the same in PHP CVS (5.0.x-dev) Built On: Mar 30, 2004 14:30 GMT

I think it is the daylight-savings-time problem. Perhaps, $tm is not checked if it is already in the daylight-savings-time. 

There are already some similar reports, but they did not get the point, and the bug has not been corrected untill  Mar 30, 2004 14:30 GMT.

Reproduce code:
echo "I have get one hour too much!<br><br>";

$to = "2004-06-01 00:00:00";
echo strtotime($to)."<br>\n";
echo strtotime("$to +1 seconds ")."<br><br>\n";
$newtime1 = strftime("%Y-%m-%d %H:%M:%S", strtotime("$to +1 seconds "));
$newtime2   = strftime("%Y-%m-%d %H:%M:%S", strtotime("$to +1 day "));

echo "$to <br>\n";
echo "+1 s= $newtime1<br>\n";
echo "+1day=$newtime2<br><br>\n";
$correct = strftime("%Y-%m-%d %H:%M:%S", strtotime("$to +1 second -1 hour"));
echo "correct: +1 s=$correct<br>";

Expected result:
If $tm is the summertime, strtotime($tm +1 day) should return 24 hours more, not 25 hours more.

If $tm is the wintertime and result is in the summertime, it should return one extra hour. 


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 [2004-03-30 12:12 UTC]
Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at and the instructions on how to report
a bug at

You need to add timezone information to the original date. 
For example change your text time to "2004-06-01 00:00:00 
The end result will be that strtotime($to) will be 1 
smaller then  strtotime("$to +1 seconds "), which is the 
correct output. 
 [2004-03-31 02:41 UTC] Hua dot Qu at volvo dot com
Thank you for quickly reply.

I still consider it as a bug. If I set 

$to = ?2004-03-28 00:00:00? 
$march0 = strftime("%Y-%m-%d %H:%M:%S", strtotime("$to"));
$march1 = strftime("%Y-%m-%d %H:%M:%S", strtotime("$to +1 second"));
$march2 = strftime("%Y-%m-%d %H:%M:%S", strtotime("$to +1 day "));

$march1 gives the correct result, while $march2 gives the wrong result. Because during the midnight of 28th it changed from the wintertime to the summertime for daylight saving. 

As you pointed out, to add a timezone:
$to = "2004-03-28 00:00:00 WET";				
$march0 = strftime("%Y-%m-%d %H:%M:%S", strtotime("$to"));
$march1 = strftime("%Y-%m-%d %H:%M:%S", strtotime("$to +1 seconds "));
$march2   = strftime("%Y-%m-%d %H:%M:%S", strtotime("$to +1 day "));

Relative to $march0, $march1 gives the correct output, but these two outputs are not what I expected. $march2 is still totally wrong no matter reference to which dates.

The point is, I think, PHP checks the output result with for daylight saving, but not the original input date.

Hua Qu
 [2004-03-31 02:56 UTC]
Right, this is a valid bug. 
 [2004-04-01 15:38 UTC]
This bug has been fixed in CVS.

Snapshots of the sources are packaged every three hours; this change
will be in the next snapshot. You can grab the snapshot at
Thank you for the report, and for helping us make PHP better.

Please test the snapshot (in 4 hours)!
 [2004-06-03 11:06 UTC] neilus at dcs dot kcl dot ac dot uk
this is re-occurring in the 4.3 tests, so either the test or bug needs to be fixed
 [2005-10-18 15:36 UTC]
This reoccurs with 5.1.0RC3 on Cygwin.

The test expects

1076824799 [2004-02-14 23:59:59 CST] [2004-04-07 00:00:00 -2 months +7 days +23 
hours +59 minutes +59 seconds]

but the result is 

1076824799 [2004-02-14 23:59:59 GMT] [2004-04-07 00:00:00 -2 months +7 days +23 hour
s +59 minutes +59 seconds]

I suppose, the test case is broken here.
 [2005-10-21 11:37 UTC]
Nothing is broken here. Cygwin's strftime() simply doesn't support it.
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