## 例

`

     bool date_default_timezone_set ( string $timezone_identifier )

`

## 説明

date_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_WARNING message if using the system settings or the TZ environment variable. Instead of using this function to set the default timezone in your script, you can also use the INI setting date.timezone to set the default timezone.

## 戻り値

This function returns FALSE if the timezone_identifier isn't valid, or TRUE otherwise.