Deal with dates in php and drupal 7

deal_with_dates_in_php_and_drupal.php

<?php
// Title: Convert to correct timezone.

// Set default time.
$date = new DateTime('2018-05-17 22:29:00', new DateTimeZone('UTC'));
print $date->format('Y-m-d H:i:s') . "\n"; // 2018-05-17 22:29:00 
// Now convert to correct timestamp.
$date->setTimezone(new DateTimeZone('Australia/Brisbane'));
print $date->format('Y-m-d H:i:s') . "\n"; // 2018-05-18 08:29:00
// ----------------------------------------------------------------
// The same as above but drupalway(using DateObject from date contrib module in drupal7).
$date = new DateObject('2018-05-17 22:29:00', new DateTimeZone('UTC'));
$date->setTimezone(new DateTimeZone('Australia/Brisbane'));
print $date->format('d/m/Y h:i:s'); // 2018-05-18 08:29:00