Add `V` format specifier for formatting and `createFromFormat`

[derickr]

Description

The following code:

<?php
$t = microtime(true);
$now = DateTime::createFromFormat('U.u', $t);
?>

Can fail, in case $t does only contain full seconds. Add V to allow for parsing any seconds + fraction of seconds, as well as add V to DateTimeInterface::format to reproduce the same value.

This would also allow for accepting any microtime(true) output.

PHP Version

PHP 8.3.3

Operating System