DateTime class and last month

Question

I have some weird behaviour with DateTime class.
Today is 2012-05-31. Timezone is "Europe/Vilnius".
Following code

 $date = new DateTime('last month');
 echo $date->format('Y-m-d');

outputs 2012-05-01. Is this a php bug? By the way, $date = new DateTime('-1 month'); outputs the same.

Answer 1

This seems to be special case for months with 31 days:

Note that '-1 month' may produce unexpected result when used in last day of month that has 31 days _{(from http://www.php.net/manual/de/datetime.formats.relative.php#102947)}

What you can do is:

$date = new DateTime('last day of last month'); // this is "2012-04-30" now
/// 'first day of last month' would work either, of course

And then it depends on what you are going to do with the date.

Answer 2

I think you need to have a datetime that already exist and modify it, like this:

<?php
$d = new DateTime( date("Y-m-d") );
$d->modify( 'last day of previous month' );
echo $d->format( 'Y-m-d' ), "\n";
?>