- date_create: documentation ( source)
- timezone_open: documentation ( source)
- date_format: documentation ( source)
- date_timezone_set: documentation ( source)
<?php
$date = date_create('2000-01-01', timezone_open('Europe/Moscow'));
echo date_format($date, 'Y-m-d H:i:sP') . PHP_EOL;
date_timezone_set($date, timezone_open('Europe/Kiev'));
echo date_format($date, 'Y-m-d H:i:sP') . PHP_EOL;