- var_dump: documentation ( source)
- timezone_identifiers_list: documentation ( source)
<?php
$allowed_zones = timezone_identifiers_list();
var_dump(count($allowed_zones));
$allowed_zones = timezone_identifiers_list(DateTimeZone::ALL, DateTimeZone::ALL_WITH_BC);
var_dump(count($allowed_zones));
$allowed_zones = timezone_identifiers_list(DateTimeZone::ALL_WITH_BC);
var_dump(count($allowed_zones));