Converting UTC to a different time zone in php - php

Question

I'm using the below method to convert the UTC time to an other time zone. But the below method seems to returning back the UTC time. Will any of you be kind enough to point out whats wrong in the method I'm using?
static function formatDateMerchantTimeZone($t, $tz) {
if (isset($t)) {
return date('Y-m-d H:i:s', strtotime($t , $tz));
} else {
return null;
}
}
$t is the datetime I pass
$tz is the time zone such as America/Los_Angeles

Answer 1

It surprises me that many people are unaware of, or do not use the DateTime classes. They make tasks like this almost trivial.
I have assumed that the date string you pass to the function is in the UTC timezone.
function formatDateMerchantTimeZone($t, $tz)
{
$date = new \DateTime($t, new \DateTimeZone('UTC'));
$date->setTimezone(new \DateTimeZone($tz));
return $date->format('Y-m-d H:i:s');
}
See it working

Answer 2

Strtotime converts a timestamp in string format to a valid date time like '09-29-2013 07:00:00' as second parameter, it does not convert a timezone to a time. php has numerous functions for timezones such as timezone_offset that does calculate the difference between two timezones. take a look in the documentation for more info:
http://php.net/manual/en/function.timezone-offset-get.php

Answer 3

static function formatDateMerchantTimeZone($t, $tz) {
if (isset($t)) {
date_default_timezone_set($tz);
return date('Y-m-d H:i:s', strtotime($t));
} else {
return null;
}
}
From php.net first comment.
To avoid frustrating confusion I recommend always calling
date_default_timezone_set('UTC') before using strtotime().
Because the UNIX Epoch is always in UTC; you will most likely output the wrong time if you do not do this.

Answer 4

try this:
<?php
/** Returns the offset from the origin timezone to the remote timezone, in seconds.
* #param $remote_tz;
* #param $origin_tz; If null the servers current timezone is used as the origin.
* #return int;
*/
function get_timezone_offset($remote_tz, $origin_tz = null) {
if($origin_tz === null) {
if(!is_string($origin_tz = date_default_timezone_get())) {
return false; // A UTC timestamp was returned -- bail out!
}
}
$origin_dtz = new DateTimeZone($origin_tz);
$remote_dtz = new DateTimeZone($remote_tz);
$origin_dt = new DateTime("now", $origin_dtz);
$remote_dt = new DateTime("now", $remote_dtz);
$offset = $origin_dtz->getOffset($origin_dt) - $remote_dtz->getOffset($remote_dt);
return $offset;
}
?>
Examples:
<?php
// This will return 10800 (3 hours) ...
$offset = get_timezone_offset('America/Los_Angeles','America/New_York');
// or, if your server time is already set to 'America/New_York'...
$offset = get_timezone_offset('America/Los_Angeles');
// You can then take $offset and adjust your timestamp.
$offset_time = time() + $offset;
?>