CODEWITHSUNDEEP
phpunix-timestamp
Adam
Adam

Reputation: 665

php strtotime end of day light saving

Ran into an issue with strtotime() and time() this morning as the time changed back 1 hour.

date_default_timezone_set('America/New_York');
$expire = strtotime('+15 minutes');
if ($expire < time()) {
// session expired
}

Between the second 1-2am period, strtotime was producing times that were less than time(), so sessions were expired on creation. Why was that?

Upvotes: 1

Views: 155

Answers (1)

Tangentially Perpendicular
Tangentially Perpendicular

Reputation: 5358

time() returns the current Unix timestamp, which, by definition is seconds since 1st January 1970, UTC. UTC doesn't observe time zones.

You're setting the time zone to America/New_York, then using strtotime() to get the current local time, which does observe time zones, hence the discrepancy.

UTC was specifically introduced to provide a consistent and continuous time reference. If you need to perform operations that rely on a consistent time reference, always use UTC.

FWIW, whenever I have to deal with time issues I set UTC everywhere (PHP, database, etc) and convert to local time in the presentation code - usually done by JavaScript on the client.

Upvotes: 2

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