PHP: How do I convert a server timestamp to the user's timezone?

Question

Hi,

I'm currently storing times using the 'time()' function in the database. However, it's using the timezone of the server, and I'd like for each user to see the time according to their timezone (set in their profile).

How do I do the timestamp conversion? (and I mean from timestamp to timestamp, not to readable time)

Your help is appreciated

Answer 1

UNIX timestamps are by definition in UTC, which means that all conversion should be done just prior to printing out rather than with actual timestamps.

How to do this however depends on how you're formatting them currently. I believe PHP has built-in timezone handling.

Answer 2

As Joonas said, UNIX timestamps are by definition UTC, but you could hack something like this together to mimic timezone-specific timestamps if you really need to:

// PHP 5.3
$timestamp = time();
echo 'Unix timestamp: ' . $timestamp;
$dt = DateTime::createFromFormat('U', $timestamp);
$dt->setTimeZone(new DateTimeZone('America/New_York'));
$adjusted_timestamp = $dt->format('U') + $dt->getOffset();
echo ' Timestamp adjusted for America/New_York: ' . $adjusted_timestamp;

// PHP 5.2
$timestamp = time();
echo 'Unix timestamp: ' . $timestamp;
$dt = date_create_from_format('U', $timestamp);
date_timezone_set($dt, new DateTimeZone('America/New_York'));
$adjusted_timestamp = date_format($dt, 'U') + date_offset_get($dt);
echo ' Timestamp adjusted for America/New_York: ' . $adjusted_timestamp;