3v4l.org

run code in 300+ PHP versions simultaneously
<?php $t1 = 1400742000; $dt = DateTime::createFromFormat('U', $t1); echo $dt->format('H:i:s'), PHP_EOL; date_add($dt, date_interval_create_from_date_string('1 hour')); echo $dt->format('H:i:s'), PHP_EOL;

preferences:
42.35 ms | 402 KiB | 5 Q