- print_r: documentation ( source)
- date_default_timezone_set: documentation ( source)
<?php
date_default_timezone_set('America/Los_Angeles');
$now = new Datetime("2013-04-09 23:45:15",new DateTimeZone("UTC"));
$lvLA = new Datetime("2013-04-09 23:44:21",new DateTimeZone('America/Los_Angeles'));
$lvUTC = new Datetime("2013-04-09 23:44:21",new DateTimeZone('UTC'));
$interval1 = $lvLA->diff($now,true);
$interval2 = $lvUTC->diff($now,true);
print_r($interval1);
print_r($interval2);