- var_dump: documentation ( source)
- date: documentation ( source)
- strtotime: documentation ( source)
<?php
var_dump($d = date('Y-\WW-w'), date('Y-m-d'));
var_dump($t = strtotime($d));
var_dump((new DateTime('@'.$t))->format('Y-\WW-w'));
var_dump((new DateTime('@'.$t))->format('Y-m-d'));
var_dump(DateTime::createFromFormat('Y-\WW-w', $d));