What is timezone of cookie stored on client's side?

Question

I need to set cookie that expires after 1 hour using PHP setcookie function. Timezone on my server is set to GMT. How should I set cookie expiry date, to make it working across different client's browser timezones?

Answer 1

PHP's setcookie() function accepts an integer corresponding to a Unix timestamp value. If your cookie should have a 1 hour time to live, you could just use time() + 3600 for that value. PHP will then create a cookie with expire time like "expires=Fri, 3 Aug 2001 20:47:11 UTC". It is in UTC (GMT) so you do not have to worry about the timezone of the client browser

Answer 2

Near as I can tell it shouldn't matter what the client time is. PHP sets the expire time based on the unix timecode. Any variation in that time should reside with the server.

Here is the excerpt from the PHP manual for setcookie():

expire:

The time the cookie expires. This is a Unix timestamp so is in number of seconds since the epoch. In other words, you'll most likely set this with the time() function plus the number of seconds before you want it to expire. Or you might use mktime(). time()+60*60*24*30 will set the cookie to expire in 30 days. If set to 0, or omitted, the cookie will expire at the end of the session (when the browser closes).