On Fri, Nov 14, 2003 at 08:53:41PM -0800, Gnik wrote:
:
: One of my servers required a PHP upgrade. Afterwards one of the PHP
: projects stopped functioning. When it would run one section would
: scroll endlessly. I can't figure out if it's a 'bug' or if it's bad
: logic in the coding.
Bad logic. But it took me a while to figure it out. I'm glad I did;
I know it will save me countless headaches in the future! :-)
: I isolated the problem to be in the 'strtotime' function. Here is a
: test I ran - when it runs, after getting to 2003-10-26, it scrolls
: incessently:
:
: ----BEGIN CODE------
: <?php
: echo "<html><head><title>Testing strtotime </title></head>";
: print " <BR>" ;
: $stop= "2003-12-27" ;
: $start= "2003-01-01" ;
: While ($start <> $stop) {
: echo "<BR> Date: " . $start ;
: $start = date('Y-m-d', strtotime($start) + 86400);
: }
: ?>
: ----END CODE------
It's a logic bug due to the wonderful world of Daylight Saving Time.
When the clock strikes 2003-10-26, adding 86400 seconds to calculate the
next day's timestamp is normally correct. However, that date is also
the last Sunday of Octobor when the U.S. officially reverts from
Daylight Saving Time back to normal time. Your next day's timestamp
"loses" one hour, i.e. 3600 seconds; your timestamp for 2003-10-27 12am
is now 2003-10-26 11pm. Because your date() call extracts only the date,
your truncation error is causing you to get stuck on 2003-10-26. This is
the cause of your infinite loop.
There are several ways to avoid this problem. The easiest way to change
date() to gmdate(). This gets you on UTC time, which is independent of
Daylight Saving Time or your timezone.
Hope this helps!
--
PHP General Mailing List (http://www.php.net/)
To unsubscribe, visit: http://www.php.net/unsub.php
