Bug #70186 [Com]: strtotime -1 month has a bug in 2015-07-31

Edit report at https://bugs.php.net/bug.php?id=70186&edit=1 ID: 70186 Comment by: vb2005xu at qq dot com Reported by: vb2005xu at qq dot com Summary: strtotime -1 month has a bug in 2015-07-31 Status: Open Type: Bug Package: Date/time related Operating System: all PHP Version: 5.6.11 Block user comment: N Private report: N New Comment: Is not just in July 31st, March 31st, May 31st, July 31st, October 31st, December 31st, there is this problem, as long as the number of days in January is less than the current number of days will appear this problem Previous Comments: ------------------------------------------------------------------------ [2015-08-03 03:00:52] vb2005xu at qq dot com Description: ------------ <?php date_default_timezone_set('Asia/Shanghai'); $tn = strtotime("2015-07-31"); echo date('Y-m' , strtotime("-1 month",$tn)); // why output 2015-07 ? Test script: --------------- <?php date_default_timezone_set('Asia/Shanghai'); $tn = strtotime("2015-07-31"); echo date('Y-m' , strtotime("-1 month",$tn)); Expected result: ---------------- 2015-06 Actual result: -------------- 2015-07 ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=70186&edit=1