Bug #75468 [Dup->Nab]: Adding +1 month using DateTime, it returns incorrect DateTime.

Edit report at https://bugs.php.net/bug.php?id=75468&edit=1 ID: 75468 Updated by: rasmus@php.net Reported by: info at milinka dot co dot uk Summary: Adding +1 month using DateTime, it returns incorrect DateTime. -Status: Duplicate +Status: Not a bug Type: Bug Package: Date/time related Operating System: any PHP Version: Irrelevant Block user comment: N Private report: N New Comment: This isn't a bug. This is how UNIX date math works. Try it from your command line (on Oct.31): $ date --date='+1 month' +'Next month is %B?' Next month is December? That's why PHP supports "first day of next month". Use that instead if you just want the next month. Previous Comments: ------------------------------------------------------------------------ [2017-10-31 10:38:49] salathe@php.net Using "+1 month" just increments the month number (e.g. "2017-10-31 +1 month" gives "2017-11-31") and when that result is not a valid date (e.g. there is no 31st of November), the normal mechanism applies and amends the date to be a valid one (e.g. the 31st day of November, is the 1st of December). See duplicate bugs: bug #75012 bug #74610 bug #73298 bug #72291 bug #70186 ... to name a few. ------------------------------------------------------------------------ [2017-10-31 10:29:34] info at milinka dot co dot uk $date = new DateTime(); $date->setDate(2017, 1, 31); $date->modify("+1 months"); var_dump($date->format('d.m.Y')); --> "2017-03-03 03:25:01.010311" ------------------------------------------------------------------------ [2017-10-31 09:48:40] info at milinka dot co dot uk Description: ------------ NOTE: This bug can replicated only today. 31 Oct 2017. When adding +1 month using DateTime, it returns incorrect DateTime. Code: $begin = new DateTime("now"); $end = clone $begin; $end->modify("+1 month"); var_dump($begin,$end); Outputs dates, where end date is wrong: object(DateTime)#1 (3) { ["date"]=> string(26) "2017-10-31 02:41:11.000000" ["timezone_type"]=> int(3) ["timezone"]=> string(10) "US/Pacific" } object(DateTime)#2 (3) { ["date"]=> string(26) "2017-12-01 02:41:11.000000" ["timezone_type"]=> int(3) ["timezone"]=> string(10) "US/Pacific" } Test script: --------------- $begin = new DateTime("now"); $end = clone $begin; $end->modify("+1 month"); var_dump($begin,$end); Expected result: ---------------- object(DateTime)#1 (3) { ["date"]=> string(26) "2017-10-31 02:41:11.000000" ["timezone_type"]=> int(3) ["timezone"]=> string(10) "US/Pacific" } object(DateTime)#2 (3) { ["date"]=> string(26) "2017-11-30 02:41:11.000000" ["timezone_type"]=> int(3) ["timezone"]=> string(10) "US/Pacific" } Actual result: -------------- object(DateTime)#1 (3) { ["date"]=> string(26) "2017-10-31 02:41:11.000000" ["timezone_type"]=> int(3) ["timezone"]=> string(10) "US/Pacific" } object(DateTime)#2 (3) { ["date"]=> string(26) "2017-12-01 02:41:11.000000" ["timezone_type"]=> int(3) ["timezone"]=> string(10) "US/Pacific" } ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=75468&edit=1