Doc #60353 [Com]: Date-related "Relative Formats" doesn't indicate month behaviour

Edit report at https://bugs.php.net/bug.php?id=60353&edit=1 ID: 60353 Comment by: teo8976 at gmail dot com Reported by: frozenfire@php.net Summary: Date-related "Relative Formats" doesn't indicate month behaviour Status: Closed Type: Documentation Problem Package: Documentation problem PHP Version: Irrelevant Assigned To: frozenfire Block user comment: N Private report: N New Comment: @frozenfire Hey man you forgot NEGATIVE values. The current explanation clearly doesn't explain how negative month values are handled. 31 december -1 months -> 1 december 31 december -2 months -> 31 october 31 december -3 months -> 1 october 31 december -4 months -> 31 august Documentation definitely needs to explain what the hell the logic behind that is, because it doesn't make any sense. Previous Comments: ------------------------------------------------------------------------ [2011-11-27 03:59:00] frozenfire@php.net This bug has been fixed in the documentation's XML sources. Since the online and downloadable versions of the documentation need some time to get updated, we would like to ask you to be a bit patient. Thank you for the report, and for helping us make our documentation better. ------------------------------------------------------------------------ [2011-11-27 03:58:45] frozenfire@php.net Automatic comment from SVN on behalf of frozenfire Revision: http://svn.php.net/viewvc/?view=revision&revision=320010 Log: Added note regarding the behaviour of relative months. Closes bug #60353. ------------------------------------------------------------------------ [2011-11-21 22:05:44] frozenfire@php.net Description: ------------ A fellow on reddit.com/r/PHP mentioned that the documentation for Relative Formats for dates is missing information on how relative months work. Here's the relevant comment: http://www.reddit.com/r/PHP/comments/mk3ub/strtotime_wtf/c31lhav "echo date("Y-m-d", strtotime("+1 month 2011-11-30")); returns: 2011-12-30 // wtf? but I wanted 2011-12-31 This is why you don't use months when calculating dates. A month is ambiguous. Think about it - since months vary, which month is it supposed to use to calculate 1 month? November or December? Since The starting date is in November, it assumes that is the first month it should start calculating from. So, for the first iteration, 1 month is 30 days. However, it recalculates what a month is for every iteration. consider this: echo date("Y-m-d", strtotime("+1 month 2011-11-30")); // 2011-12-30 or 30 days echo date("Y-m-d", strtotime("+2 month 2011-11-30")); // 2012-01-30 or 61 days echo date("Y-m-d", strtotime("+30 days 2011-11-30")); // 2011-12-30 echo date("Y-m-d", strtotime("+60 days 2011-11-30")); // 2012-01-29 Notice how when I use +2 months it suddenly becomes 61 days. This is because it starts in December on the second iteration, and it recalculates what a month is based on that." This behaviour should be documented in the datetime.formats.relative document. ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=60353&edit=1