- date_default_timezone_set: documentation ( source)
- date_default_timezone_get: documentation ( source)
<?php
date_default_timezone_set('Europe/Prague');
$d1 = new DateTime('@-21474836470');
$d1->setTimezone(new DateTimeZone(date_default_timezone_get()));
echo $d1->format('c');
echo ' ';
echo $d1->format('U');
echo "\n";
$d2 = new DateTime('1289-06-27 16:38:50');
echo $d2->format('c');
echo ' ';
echo $d2->format('U');
echo "\n";
echo $d1 == $d2 ? 'true' : 'false';