/**
* undocumented function
*
* @param unknown $groups
* @param unknown $includeOffset
* @return void
* @access public
*/
static function listByGroups($groups = array(), $includeOffset = true)
{
if (empty($groups)) {
$groups = TimeZone::listGroups();
}
$allZones = DateTimeZone::listIdentifiers();
$listZones = array();
foreach ($allZones as $zone) {
@(list($group, $city) = explode('/', $zone));
if (!in_array($group, $groups)) {
} elseif ($includeOffset) {
$offset = TimeZone::offset($zone);
$sign = $offset < 0 ? '-' : '+';
$offset = date('H:i', mktime(0, 0, abs($offset)));
$listZones[$group][] = $city . ' (GMT ' . $sign . $offset . ')';
}
}
foreach ($listZones as $group => $data) {
$listZones[$group] = array_unique($listZones[$group]);
}
return $listZones;
}