Date parser doesn't speak ISO weekdates

[hgshoggins]

Description

The following code:

<?php
$dateTimeObj_monday = new DateTimeImmutable('2022W1', new DateTimeZone('Europe/Paris'));

Resulted in this output:

PHP Fatal error:  Uncaught DateMalformedStringException: Failed to parse time string (2022W1) at position 5 (1): Unexpected character in test.php:7
Stack trace:
#0 /root/test.php(7): DateTimeImmutable->__construct()

But I expected this output instead: a correctly set DateTimeImmutable object.

It seems that the parser refuses to recognize the "W" for week specification.

PHP Version

PHP 8.4.14 (cli) (built: Oct 21 2025 19:23:55) (NTS gcc x86_64)
Copyright (c) The PHP Group
Built by Fedora Project
Zend Engine v4.4.14, Copyright (c) Zend Technologies

Operating System

Fedora 42

[devnexen]

From PHP POV, it is not fully valid, e.g. something in the form of 2022-W01-1 is expected.

[MorganLOCode]

2022W1 doesn't work.
2022W01 does.
I.e., the week needs two digits (and the day then defaults to Monday, of course).

[hgshoggins]

Thank you, I should have tried that before really scratching my head on that. Now I guess a sprintf('%02d', $weekNumber) is the way to go.