(PHP 5 >= 5.1.0RC1)
date_default_timezone_set -- Sets the default timezone used by all date/time functions in a scriptdate_default_timezone_set() sets the default timezone used by all date/time functions.
Note: Since PHP 5.1.0 (when the date/time functions were rewritten), every call to a date/time function will generate a E_NOTICE if the timezone isn't valid, and/or a E_STRICT message if using the system settings or the TZ environment variable.
The timezone identifier, like UTC or Europe/Lisbon. The list of valid identifiers is available in the Appendix H.
This function returns FALSE if the timezone_identifier isn't valid, or TRUE otherwise.