TIMEZONE选择框仅更改为美国

Question

I have a bit of code that populates a selectbox with timezones however it includes Asia, Africa, etc. I would like to only have it list US timezones. Is that possible? The code I have now is...

    /*
    Get all timezone listing
    */
    function event_tz_list() {
      $zones_array = array();
      $timestamp = time();
      foreach(timezone_identifiers_list() as $key => $zone) {
        date_default_timezone_set($zone);
        $zones_array[$key]['zone'] = $zone;
        $zones_array[$key]['offset'] = date('P', $timestamp);
        $zones_array[$key]['diff_from_GMT'] = 'UTC/GMT ' . date('P', 
    $timestamp);
      }
      return $zones_array;

    }

Any information would be greatly appreciated!

Answer 1

timezone_identifiers_list() takes two arguments. A constant for what timezones to get and a two letter country code if the first argument is DateTimeZone::PER_COUNTRY. So this will pretty much get it:

timezone_identifiers_list(DateTimeZone::PER_COUNTRY, 'US')

If you want to get the 7 abbreviations instead of the 29 America/City values:

function event_tz_list() {
    foreach(timezone_identifiers_list(DateTimeZone::PER_COUNTRY, 'US') as $key => $zone) {
        $timestamp = time();
        date_default_timezone_set($zone);
        $abbrev = date('T'); // use as the key and you won't get duplicates
        $zones_array[$abbrev]['zone'] = $abbrev;
        $zones_array[$abbrev]['offset'] = date('P', $timestamp);
        $zones_array[$abbrev]['diff_from_GMT'] = 'UTC/GMT ' . date('P', $timestamp);
    }
    return $zones_array;
}

print_r(event_tz_list());

Yields:

Array
(
    [HAST] => Array
        (
            [zone] => HAST
            [offset] => -10:00
            [diff_from_GMT] => UTC/GMT -10:00
        )

    [AKST] => Array
        (
            [zone] => AKST
            [offset] => -09:00
            [diff_from_GMT] => UTC/GMT -09:00
        )

    [MST] => Array
        (
            [zone] => MST
            [offset] => -07:00
            [diff_from_GMT] => UTC/GMT -07:00
        )

    [CST] => Array
        (
            [zone] => CST
            [offset] => -06:00
            [diff_from_GMT] => UTC/GMT -06:00
        )

    [EST] => Array
        (
            [zone] => EST
            [offset] => -05:00
            [diff_from_GMT] => UTC/GMT -05:00
        )

    [PST] => Array
        (
            [zone] => PST
            [offset] => -08:00
            [diff_from_GMT] => UTC/GMT -08:00
        )

    [HST] => Array
        (
            [zone] => HST
            [offset] => -10:00
            [diff_from_GMT] => UTC/GMT -10:00
        )

)

Which shows 7 timezones (I learned something):

There is no time difference between Hawaii-Aleutian Standard Time (HAST) and Hawaii Standard Time (HST).