Bug #52480 [Csd->ReO]: Incorrect difference using DateInterval

Edit report at https://bugs.php.net/bug.php?id=52480&edit=1

 ID:                 52480
 Updated by:         [email protected]
 Reported by:        alex dot joyce at staff dot comcen dot com dot au
 Summary:            Incorrect difference using DateInterval
-Status:             Closed
+Status:             Re-Opened
 Type:               Bug
 Package:            Date/time related
-Operating System:   Debian 5.0.3
+Operating System:   irrelevant
-PHP Version:        5.3.3
+PHP Version:        7.1
 Assigned To:        derick
 Block user comment: N
 Private report:     N

 New Comment:

That (https://3v4l.org/1b6fj) looks like a shift of the month number to me. Derick, could you have a look at that?


Previous Comments:
------------------------------------------------------------------------
[2017-03-20 11:44:08] [email protected]

Happens for March https://3v4l.org/R3LLN but not May https://3v4l.org/nblYg. DST?

------------------------------------------------------------------------
[2017-03-20 11:22:55] tomasz dot majerski at o2 dot pl

Don't close this issue. PHP 7.0.6 still not getting expected results...

$date_start = '2017-03-01';
$date_end = '2017-03-31';

DateInterval Object
(
    [y] => 0
    [m] => 1
    [d] => 2
    [h] => 0
    [i] => 0
    [s] => 0
    [weekday] => 0
    [weekday_behavior] => 0
    [first_last_day_of] => 0
    [invert] => 0
    [days] => 30
    [special_type] => 0
    [special_amount] => 0
    [have_weekday_relative] => 0
    [have_special_relative] => 0
)

------------------------------------------------------------------------
[2017-03-19 09:58:41] [email protected]

This seems to be fixed in supported versions of PHP. Therefore I'm closing this issue.

php > $date_start = new DateTime('2010-03-01');
php >   $date_end   = new DateTime('2010-07-29');
php >
php >   $interval = $date_start->diff($date_end);
php >
php >   print_r($interval);
DateInterval Object
(
    [y] => 0
    [m] => 4
    [d] => 28
    [h] => 0
    [i] => 0
    [s] => 0
    [f] => 0
    [weekday] => 0
    [weekday_behavior] => 0
    [first_last_day_of] => 0
    [invert] => 0
    [days] => 150
    [special_type] => 0
    [special_amount] => 0
    [have_weekday_relative] => 0
    [have_special_relative] => 0
)

------------------------------------------------------------------------
[2016-11-23 07:14:51] lebeker at gmail dot com

Still got a problems:

(new DateTime('2016-10-01'))->diff((new DateTime('2016-10-31'))) // 1 month
(new DateTime('2016-11-01'))->diff((new DateTime('2016-11-30'))) // 29 days
either first should be 30 days, or the second one 1 month

(new DateTime('2016-11-01'))->diff((new DateTime('2016-12-01'))) // 30 days
but that's definitely 1 whole month

and what's more interesting
(new DateTime('2016-11-01'))->diff((new DateTime('2016-11-31'))) // 30 days
but there is no such date as '2016-11-31', but that's probably another bug.


PHP 7.0.8-0ubuntu0.16.04.3

------------------------------------------------------------------------
[2016-02-12 01:56:26] pinballfan at outlook dot com

After trying Marcel's code I got the same 'problem' on PHP 5.6 on a 64bit Windows 10 machine.  However unexpected the result, I believe it is consistent with how PHP's datetime rounds dates around.  Using this example:

$date1 = new DateTime('2011-08-31T00:00:00Z');
$date2 = new DateTime('2012-03-01T00:00:00Z');
$interval = $date1->diff($date2);
var_dump($interval);

$interval->m = 5
$interval->d = 30

The expectation might be 6 months and 1 day

What I'm guessing might be happening is that PHP starts adding 1 month like so:
2011-08-31 = starting date
2011-09-31 = starting date + 1 month (but there is no such thing as sept 31!)
2011-10-01 = date now wraps around to 2011-10-01 since
             2011-09-31 doesn't exist
2011-11-01 = + 1 month (2 total)
2011-12-01 = + 1 month (3 total)
2012-01-01 = + 1 month (4 total)
2012-02-01 = + 1 month (5 total)
2012-03-01 = When diff'ing PHP does NOT include the final date maybe like DatePeriod.

So that could be how it arrived at 5m and 30d

------------------------------------------------------------------------


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