Bug #73644 [Com]: Datetime::diff returns wrong number of month difference

Edit report at https://bugs.php.net/bug.php?id=73644&edit=1 ID: 73644 Comment by: john dot mannard at yahoo dot fr Reported by: john dot mannard at yahoo dot fr Summary: Datetime::diff returns wrong number of month difference Status: Not a bug Type: Bug Package: Date/time related PHP Version: 7.1.0 Assigned To: cmb Block user comment: N Private report: N New Comment: Thank you for your answer. Previous Comments: ------------------------------------------------------------------------ [2016-12-02 18:05:39] cmb@php.net The first $date1 and $threemonthsago also include the current time, but the second $date1 does not, see <https://3v4l.org/Ev1BM>. This behavior is intentional, and also the following results. ------------------------------------------------------------------------ [2016-12-02 16:12:40] john dot mannard at yahoo dot fr Description: ------------ Hi, I executed this piece of code yesterday and have the feeling there may be a problem in how Datetime object parses strings. The "new DateTime()" instruction returns a DateTime object with current date. The "new DateTime('yyyy-mm-dd') return a DateTime object with date given. Depending on how you instantiate, interval returned by the diff method will not return same amount of months. In code below, if you comment line 2 or not, the m property of DateInterval obkect will not be the same (in one case it is 3, in the other it is 2). I have the feeling that these two ways of instantiating a DateTime should process a difference with another the date the same way. Am I wrong on this topic? Thanking you in advance. Test script: --------------- $date1 = new DateTime(); $date1 = new DateTime($date1->format('Y-m-d')); // If commented, not same result in number of months $threemonthsago = new DateTime('3 months ago'); $diff = $threemonthsago->diff($date1); echo 'Number of months: '.($diff->m + 12*$diff->y );echo '<br/>'; echo '$date1 in d-m-Y format: '.$date1->format('d-m-Y');echo '<br/>'; echo '$threemonthsago in d-m-Y format: '. $threemonthsago->format('d-m-Y'); Expected result: ---------------- In the code above, first echo should always be 3 months. Actual result: -------------- In the code above, if second line is commented, it shows 3, otherwise 2. ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=73644&edit=1