Practicing the fundamentals: Timezone handling

Timezone handling can sometimes be a bitch. Turns out, using a couple of PHPs classes and functions, it’s quite easy.

Let’s say you have a web application with the following scenario:
Users from around the planet, and your server is located in the UK.

You would initialize your DateTime object like this:

$timezoneUTC = new DateTimeZone('UTC');
$dateTime = new DateTime('2012-02-23 10:22', $timezoneUTC);

echo $dateTime->format('Y-m-d H:i e').'<br/>';

This should output:
2012-02-23 10:22 UTC

For an international user, seeing his or her local time would be nice.
To do this, simply change the timezone of the existing DateTime object, like this:

$timeZoneSweden = new DateTimeZone('Europe/Stockholm');
$dateTime->setTimeZone($timeZoneSweden);
echo $dateTime->format('Y-m-d H:i e').'<br/>';

$timeZoneNY = new DateTimeZone('America/New_York');
$dateTime->setTimeZone($timeZoneNY);
echo $dateTime->format('Y-m-d H:i e').'<br/>';

$timeZoneBKK = new DateTimeZone('Asia/Bangkok');
$dateTime->setTimeZone($timeZoneBKK);
echo $dateTime->format('Y-m-d H:i e').'<br/>';

This should output:
2012-02-23 11:22 Europe/Stockholm
2012-02-23 05:22 America/New_York
2012-02-23 17:22 Asia/Bangkok

The final code should look something like this:

$timezoneUTC = new DateTimeZone('UTC');
$timeZoneSweden = new DateTimeZone('Europe/Stockholm');
$dateTime = new DateTime('2012-02-23 10:22', $timezoneUTC);
$dateTime->setTimeZone($timeZoneSweden);

This will leave a DateTime object set with the users timezone.

And that’s it.