PHP 5.2

Changes in PHP datetime support

Since PHP 5.1.0, there has been an extension named date in the PHP core. This is the new implementation of PHP's datetime support. Although it will attempt to guess your system's timezone setting, you should set the timezone manually. You can do this in any of three ways:

in your php.ini using the date.timezone INI directive
on your system using the TZ environmental variable
from your script using the convenience function date_default_timezone_set()

All supported timezones are listed in the PHP Manual.

With the advent of PHP 5.2.x, there are object representations of the date and timezone, named DateTime and DateTimeZone respectively. The methods map to existing procedural date functions.

PHP 5.1

Date/time support

Date/time support has been fully rewritten in PHP 5.1.x, and no longer uses the system settings to 'know' the timezone in operation. It will instead utilize, in the following order:

The timezone set using the date_default_timezone_set() function (if any)
The TZ environment variable (if non empty)
"magical" guess (if the operating system supports it)
If none of the above options succeeds, UTC

To ensure accuracy (and avoid an E_STRICT warning), you will need to define your timezone in your php.ini using the following format:

date.timezone = Europe/London

The supported timezones are listed, in this format, in the timezones appendix.

Also note that strtotime() now returns FALSE on failure, instead of -1.