Bug #73298 [Opn->Nab]: DateTime::add adding 1 month on 31st of August skips to October

Edit report at https://bugs.php.net/bug.php?id=73298&edit=1 ID: 73298 Updated by: requinix@php.net Reported by: enachesilviu at live dot com Summary: DateTime::add adding 1 month on 31st of August skips to October -Status: Open +Status: Not a bug Type: Bug Package: Date/time related Operating System: CentOS 6 PHP Version: Irrelevant Block user comment: N Private report: N New Comment: PHP follows standard *nix behavior of overflowing the date: 2016-08-31 + 1 month = 2016-09-31 which overflows to 2016-10-01. Meanwhile Java's add() specifically does not do that: see the "Field Manipulation" section in the documentation for java.util.Calendar <https://docs.oracle.com/javase/7/docs/api/java/util/Calendar.html>. Previous Comments: ------------------------------------------------------------------------ [2016-10-12 04:09:18] enachesilviu at live dot com Description: ------------ DateTime::add adding 1 month on 31st of August skips to October I did a similar snippet in Java and I get the expected result: import java.util.*; import java.text.*; import java.lang.*; class TestingDateTime { public static void main (String[] args) throws java.lang.Exception { SimpleDateFormat ft = new SimpleDateFormat ("yyyy-MM-dd"); Date date = ft.parse("2016-08-31"); System.out.println("Initial value:"); System.out.println(ft.format(date)); Calendar calendar = Calendar.getInstance(); calendar.setTime(date); calendar.add(Calendar.MONTH, 1); date = calendar.getTime(); System.out.println("\nNew value:"); System.out.println(ft.format(date)); } } Test script: --------------- <?php function printline($value) { $separator = 'cli' == php_sapi_name() ? PHP_EOL : '<br/>'; echo $value . $separator; } $dateTime = new DateTime('2016-08-31 00:00:00'); printline('Initial value: ' . $dateTime->format('Y-m-d H:i:s')); $dateTime->add(new DateInterval('P1M')); printline('New value: ' . $dateTime->format('Y-m-d H:i:s')); Expected result: ---------------- 2016-09-30 00:00:00 Actual result: -------------- 2016-10-01 00:00:00 ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=73298&edit=1