ID: 22486
Updated by: tac...@php.net
Reported By: drwav at hotpop dot com
Status: Bogus
Bug Type: Date/time related
-Operating System: Win32
+Operating System: Irrelevant
PHP Version: 4.2.3
New Comment:
I agree that this is an annoying behaviour.
Also, the implementation is problematic. Basically if you use '+1
month' it takes the month number, adds 1 and parses result as a new
date.
If you use '+1 month' on the first of the month, it sets the date to
the next first of the month.
This behaviour gives the impression, that php considers the length of a
month, which is not true.
But if you use '+1 month' on the last day of a month, the result is
unexpected as 2009-05-31 becomes 2009-06-31 which is an invalid date and
then interpreted as 2009-07-01.
This should at least be mentioned in the documentation.
Previous Comments:
------------------------------------------------------------------------
[2004-08-31 17:25:57] kotala at ingema dot net
I have to agree tuxedobob at mac dot com and I would like you to think
about that once more:
- if I want something 31 day in the future, I would use '+31 days'
- now I was filling new bug report, because my web worked good in 2
months testing period - and now, as stable system, just DO NOT WORK for
one day - and all because we didn't came to idea of nonstandard
behaviour in 31st
If you decide not to correct this, than please write it in big red
letters in documentation at least, because this is nearly undebuggable!
------------------------------------------------------------------------
[2003-03-01 09:32:58] ras...@php.net
Well, we'll have to agree to disagree. A month is a period of time
just like a second, a minute and an hour. It is not as well-defined
since it varies from one month to the next, but on the average it is
30.5 days. Without further context, if you simply say that something
will take a month or you use "a month" without specifying which month,
the only correct assumption to make is that it is a period of time
approximately 30.5 days.
This is exactly the same problem you have if you simply add a month to
the mktime() month argument without changing the day. If you tell
mktime to give you the unix timestamp for Feb. 30, it is going to give
you the timestamp for March 2. If what you really want is the timestamp
for the 1st day of the next month, simply get the current month and add
1 to it and feed it the day in the next month you want in your mktime
call. eg.
$t = mktime(12,0,0,date('n')+1,10,date('Y'));
That will give you the timestame for noon on the 10th day of the next
month in the current year.
Any change to what a month is in the current strtotime() code is going
to break a lot of applications as most people want and expect the
current behaviour.
And relax, I was just kidding with the example. I won't actually show
up and beat the crap out of you in a month.
------------------------------------------------------------------------
[2003-03-01 02:12:16] tuxedobob at mac dot com
Yes, it would be more correct. The month after January is Feburary. It
follows that adding a month to a day in January should get you a day in
February. Likewise, adding a month to March 31 currently gets you May
1st, but should result in April 30.
strtotime clearly isn't simply tacking on some number of days, since a
month after 1/1 is 2/1 and 2/1 + 1 month is 3/1. It can even handle leap
years correctly. It should really do a bit more thinking with regards to
this.
As for your example, either you're just being a prick, or you've been
watching a little too much Pirates of Penzance.
------------------------------------------------------------------------
[2003-02-28 23:38:30] ras...@php.net
But would choosing Feb.28 really be any more correct? If I told you on
January 30 that I would come back in exactly one month to beat the crap
out of you, when would you think I would show up?
------------------------------------------------------------------------
[2003-02-28 23:34:53] drwav at hotpop dot com
when strtotime is asked to create a timestaml +1 month in the future,
and is given a timestamp that happens on a day that does not exist in
the next month. A timestamp a few days beyond one month in the future is
created.
Example:
<?php
$now = strtotime("2003-01-30");
$nextmonth = strtotime("+1 month", $now);
print date("Y-m-d", $nextmonth);
?>
the output from this script is
2003-03-02
since February has no 30th day, apparently strtotime just adds 30 days
to whatever timestamp it is given to go one month in the future, hence
March 2nd.
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