DateTime::createFromFormat bug

[gabriel-dina]

Description

Run the following code on the 31 day of the current month (ex. october):

$dt = \DateTime::createFromFormat('Y-n','2024-11'); echo date("t", $dt->getTimestamp());
Resulted in this output:
31

But I expected this output instead:
30

Workaround:
$dt = \DateTime::createFromFormat('Y-n-d','2024-11-01'); echo date("t", $dt->getTimestamp());

PHP Version

PHP 8

Operating System

Ubuntu 20

[damianwadley]

https://www.php.net/manual/en/datetimeimmutable.createfromformat.php

All fields are initialised with the current date/time. In most cases you would want to reset these to "zero" (the Unix epoch, 1970-01-01 00:00:00 UTC). You do that by including the ! character as first character in your format, or | as your last.

Since today's date is October 31st (for most of the world), it's effectively using the date 2024-11-31, which overflows into December, which has 31 days.

As mentioned in the documentation, you probably want to be using ! like

$dt =  \DateTime::createFromFormat('!Y-n','2024-11');
echo date("t", $dt->getTimestamp());

https://3v4l.org/8EJuc

[gabriel-dina]

I never got to the end of that doc page. Thank you!