Generazione di un elenco a discesa di fusi orari con PHP

La maggior parte dei siti ha bisogno di un modo per mostrare le date sul sito nel fuso orario preferito dagli utenti. Di seguito sono riportati due elenchi che ho trovato e quindi un metodo che utilizza la classe PHT DateTime incorporata in PHP 5.

Ho bisogno di aiuto per sapere quale di questi sarebbe il migliore da provare quando si tenta di ottenere l'offset UTC dall'utente sul registro.

Uno:

<option value="-12">[UTC - 12] Baker Island Time</option>
<option value="-11">[UTC - 11] Niue Time, Samoa Standard Time</option>
<option value="-10">[UTC - 10] Hawaii-Aleutian Standard Time, Cook Island Time</option>
<option value="-9.5">[UTC - 9:30] Marquesas Islands Time</option>
<option value="-9">[UTC - 9] Alaska Standard Time, Gambier Island Time</option>
<option value="-8">[UTC - 8] Pacific Standard Time</option>
<option value="-7">[UTC - 7] Mountain Standard Time</option>
<option value="-6">[UTC - 6] Central Standard Time</option>
<option value="-5">[UTC - 5] Eastern Standard Time</option>
<option value="-4.5">[UTC - 4:30] Venezuelan Standard Time</option>
<option value="-4">[UTC - 4] Atlantic Standard Time</option>
<option value="-3.5">[UTC - 3:30] Newfoundland Standard Time</option>
<option value="-3">[UTC - 3] Amazon Standard Time, Central Greenland Time</option>
<option value="-2">[UTC - 2] Fernando de Noronha Time, South Georgia &amp; the South Sandwich Islands Time</option>
<option value="-1">[UTC - 1] Azores Standard Time, Cape Verde Time, Eastern Greenland Time</option>
<option value="0" selected="selected">[UTC] Western European Time, Greenwich Mean Time</option>
<option value="1">[UTC + 1] Central European Time, West African Time</option>
<option value="2">[UTC + 2] Eastern European Time, Central African Time</option>
<option value="3">[UTC + 3] Moscow Standard Time, Eastern African Time</option>
<option value="3.5">[UTC + 3:30] Iran Standard Time</option>
<option value="4">[UTC + 4] Gulf Standard Time, Samara Standard Time</option>
<option value="4.5">[UTC + 4:30] Afghanistan Time</option>
<option value="5">[UTC + 5] Pakistan Standard Time, Yekaterinburg Standard Time</option>
<option value="5.5">[UTC + 5:30] Indian Standard Time, Sri Lanka Time</option>
<option value="5.75">[UTC + 5:45] Nepal Time</option>
<option value="6">[UTC + 6] Bangladesh Time, Bhutan Time, Novosibirsk Standard Time</option>
<option value="6.5">[UTC + 6:30] Cocos Islands Time, Myanmar Time</option>
<option value="7">[UTC + 7] Indochina Time, Krasnoyarsk Standard Time</option>
<option value="8">[UTC + 8] Chinese Standard Time, Australian Western Standard Time, Irkutsk Standard Time</option>
<option value="8.75">[UTC + 8:45] Southeastern Western Australia Standard Time</option>
<option value="9">[UTC + 9] Japan Standard Time, Korea Standard Time, Chita Standard Time</option>
<option value="9.5">[UTC + 9:30] Australian Central Standard Time</option>
<option value="10">[UTC + 10] Australian Eastern Standard Time, Vladivostok Standard Time</option>
<option value="10.5">[UTC + 10:30] Lord Howe Standard Time</option>
<option value="11">[UTC + 11] Solomon Island Time, Magadan Standard Time</option>
<option value="11.5">[UTC + 11:30] Norfolk Island Time</option>
<option value="12">[UTC + 12] New Zealand Time, Fiji Time, Kamchatka Standard Time</option>
<option value="12.75">[UTC + 12:45] Chatham Islands Time</option>
<option value="13">[UTC + 13] Tonga Time, Phoenix Islands Time</option>
<option value="14">[UTC + 14] Line Island Time</option>

O usando valori compatibili con PHP:

<option value="Pacific/Midway">(GMT-11:00) Midway Island, Samoa</option>
<option value="America/Adak">(GMT-10:00) Hawaii-Aleutian</option>
<option value="Etc/GMT+10">(GMT-10:00) Hawaii</option>
<option value="Pacific/Marquesas">(GMT-09:30) Marquesas Islands</option>
<option value="Pacific/Gambier">(GMT-09:00) Gambier Islands</option>
<option value="America/Anchorage">(GMT-09:00) Alaska</option>
<option value="America/Ensenada">(GMT-08:00) Tijuana, Baja California</option>
<option value="Etc/GMT+8">(GMT-08:00) Pitcairn Islands</option>
<option value="America/Los_Angeles">(GMT-08:00) Pacific Time (US & Canada)</option>
<option value="America/Denver">(GMT-07:00) Mountain Time (US & Canada)</option>
<option value="America/Chihuahua">(GMT-07:00) Chihuahua, La Paz, Mazatlan</option>
<option value="America/Dawson_Creek">(GMT-07:00) Arizona</option>
<option value="America/Belize">(GMT-06:00) Saskatchewan, Central America</option>
<option value="America/Cancun">(GMT-06:00) Guadalajara, Mexico City, Monterrey</option>
<option value="Chile/EasterIsland">(GMT-06:00) Easter Island</option>
<option value="America/Chicago">(GMT-06:00) Central Time (US & Canada)</option>
<option value="America/New_York">(GMT-05:00) Eastern Time (US & Canada)</option>
<option value="America/Havana">(GMT-05:00) Cuba</option>
<option value="America/Bogota">(GMT-05:00) Bogota, Lima, Quito, Rio Branco</option>
<option value="America/Caracas">(GMT-04:30) Caracas</option>
<option value="America/Santiago">(GMT-04:00) Santiago</option>
<option value="America/La_Paz">(GMT-04:00) La Paz</option>
<option value="Atlantic/Stanley">(GMT-04:00) Faukland Islands</option>
<option value="America/Campo_Grande">(GMT-04:00) Brazil</option>
<option value="America/Goose_Bay">(GMT-04:00) Atlantic Time (Goose Bay)</option>
<option value="America/Glace_Bay">(GMT-04:00) Atlantic Time (Canada)</option>
<option value="America/St_Johns">(GMT-03:30) Newfoundland</option>
<option value="America/Araguaina">(GMT-03:00) UTC-3</option>
<option value="America/Montevideo">(GMT-03:00) Montevideo</option>
<option value="America/Miquelon">(GMT-03:00) Miquelon, St. Pierre</option>
<option value="America/Godthab">(GMT-03:00) Greenland</option>
<option value="America/Argentina/Buenos_Aires">(GMT-03:00) Buenos Aires</option>
<option value="America/Sao_Paulo">(GMT-03:00) Brasilia</option>
<option value="America/Noronha">(GMT-02:00) Mid-Atlantic</option>
<option value="Atlantic/Cape_Verde">(GMT-01:00) Cape Verde Is.</option>
<option value="Atlantic/Azores">(GMT-01:00) Azores</option>
<option value="Europe/Belfast">(GMT) Greenwich Mean Time : Belfast</option>
<option value="Europe/Dublin">(GMT) Greenwich Mean Time : Dublin</option>
<option value="Europe/Lisbon">(GMT) Greenwich Mean Time : Lisbon</option>
<option value="Europe/London">(GMT) Greenwich Mean Time : London</option>
<option value="Africa/Abidjan">(GMT) Monrovia, Reykjavik</option>
<option value="Europe/Amsterdam">(GMT+01:00) Amsterdam, Berlin, Bern, Rome, Stockholm, Vienna</option>
<option value="Europe/Belgrade">(GMT+01:00) Belgrade, Bratislava, Budapest, Ljubljana, Prague</option>
<option value="Europe/Brussels">(GMT+01:00) Brussels, Copenhagen, Madrid, Paris</option>
<option value="Africa/Algiers">(GMT+01:00) West Central Africa</option>
<option value="Africa/Windhoek">(GMT+01:00) Windhoek</option>
<option value="Asia/Beirut">(GMT+02:00) Beirut</option>
<option value="Africa/Cairo">(GMT+02:00) Cairo</option>
<option value="Asia/Gaza">(GMT+02:00) Gaza</option>
<option value="Africa/Blantyre">(GMT+02:00) Harare, Pretoria</option>
<option value="Asia/Jerusalem">(GMT+02:00) Jerusalem</option>
<option value="Europe/Minsk">(GMT+02:00) Minsk</option>
<option value="Asia/Damascus">(GMT+02:00) Syria</option>
<option value="Europe/Moscow">(GMT+03:00) Moscow, St. Petersburg, Volgograd</option>
<option value="Africa/Addis_Ababa">(GMT+03:00) Nairobi</option>
<option value="Asia/Tehran">(GMT+03:30) Tehran</option>
<option value="Asia/Dubai">(GMT+04:00) Abu Dhabi, Muscat</option>
<option value="Asia/Yerevan">(GMT+04:00) Yerevan</option>
<option value="Asia/Kabul">(GMT+04:30) Kabul</option>
<option value="Asia/Yekaterinburg">(GMT+05:00) Ekaterinburg</option>
<option value="Asia/Tashkent">(GMT+05:00) Tashkent</option>
<option value="Asia/Kolkata">(GMT+05:30) Chennai, Kolkata, Mumbai, New Delhi</option>
<option value="Asia/Katmandu">(GMT+05:45) Kathmandu</option>
<option value="Asia/Dhaka">(GMT+06:00) Astana, Dhaka</option>
<option value="Asia/Novosibirsk">(GMT+06:00) Novosibirsk</option>
<option value="Asia/Rangoon">(GMT+06:30) Yangon (Rangoon)</option>
<option value="Asia/Bangkok">(GMT+07:00) Bangkok, Hanoi, Jakarta</option>
<option value="Asia/Krasnoyarsk">(GMT+07:00) Krasnoyarsk</option>
<option value="Asia/Hong_Kong">(GMT+08:00) Beijing, Chongqing, Hong Kong, Urumqi</option>
<option value="Asia/Irkutsk">(GMT+08:00) Irkutsk, Ulaan Bataar</option>
<option value="Australia/Perth">(GMT+08:00) Perth</option>
<option value="Australia/Eucla">(GMT+08:45) Eucla</option>
<option value="Asia/Tokyo">(GMT+09:00) Osaka, Sapporo, Tokyo</option>
<option value="Asia/Seoul">(GMT+09:00) Seoul</option>
<option value="Asia/Yakutsk">(GMT+09:00) Yakutsk</option>
<option value="Australia/Adelaide">(GMT+09:30) Adelaide</option>
<option value="Australia/Darwin">(GMT+09:30) Darwin</option>
<option value="Australia/Brisbane">(GMT+10:00) Brisbane</option>
<option value="Australia/Hobart">(GMT+10:00) Hobart</option>
<option value="Asia/Vladivostok">(GMT+10:00) Vladivostok</option>
<option value="Australia/Lord_Howe">(GMT+10:30) Lord Howe Island</option>
<option value="Etc/GMT-11">(GMT+11:00) Solomon Is., New Caledonia</option>
<option value="Asia/Magadan">(GMT+11:00) Magadan</option>
<option value="Pacific/Norfolk">(GMT+11:30) Norfolk Island</option>
<option value="Asia/Anadyr">(GMT+12:00) Anadyr, Kamchatka</option>
<option value="Pacific/Auckland">(GMT+12:00) Auckland, Wellington</option>
<option value="Etc/GMT-12">(GMT+12:00) Fiji, Kamchatka, Marshall Is.</option>
<option value="Pacific/Chatham">(GMT+12:45) Chatham Islands</option>
<option value="Pacific/Tongatapu">(GMT+13:00) Nuku'alofa</option>
<option value="Pacific/Kiritimati">(GMT+14:00) Kiritimati</option>

O semplicemente usando PHP stesso:

$timezones = DateTimeZone::listAbbreviations();

$cities = array();
foreach( $timezones as $key => $zones )
{
    foreach( $zones as $id => $zone )
    {
        /**
         * Only get timezones explicitely not part of "Others".
         * @see http://www.php.net/manual/en/timezones.others.php
         */
        if ( preg_match( '/^(America|Antartica|Arctic|Asia|Atlantic|Europe|Indian|Pacific)\//', $zone['timezone_id'] ) 
            && $zone['timezone_id']) {
            $cities[$zone['timezone_id']][] = $key;
        }
    }
}

// For each city, have a comma separated list of all possible timezones for that city.
foreach( $cities as $key => $value )
    $cities[$key] = join( ', ', $value);

// Only keep one city (the first and also most important) for each set of possibilities. 
$cities = array_unique( $cities );

// Sort by area/city name.
ksort( $cities );

Sembra che l'ultimo sarebbe il più sicuro in quanto sarebbe cresciuto con la versione di PHP utilizzata. È inoltre possibile capovolgere tale array quando necessario per collegare i fusi orari ai nomi delle città.

Lo farei in PHP, tranne che eviterei di fare preg_match 100 alcune volte e lo farei per generare la tua lista.

$tzlist = DateTimeZone::listIdentifiers(DateTimeZone::ALL);

Inoltre, userei i nomi di PHP per i "fusi orari" e dimenticherei gli offset GMT, che cambieranno in base all'ora legale. Codice come quello in phpbb è solo in questo modo b / c supportano ancora PHP4 e non possono fare affidamento sugli oggetti DateTime o DateTimeZone presenti.

Seguendo l'esempio di user210179 sopra, ho scritto la seguente funzione per generare un elenco di tutti i fusi orari con i loro offset:

function generate_timezone_list()
{
    static $regions = array(
        DateTimeZone::AFRICA,
        DateTimeZone::AMERICA,
        DateTimeZone::ANTARCTICA,
        DateTimeZone::ASIA,
        DateTimeZone::ATLANTIC,
        DateTimeZone::AUSTRALIA,
        DateTimeZone::EUROPE,
        DateTimeZone::INDIAN,
        DateTimeZone::PACIFIC,
    );

    $timezones = array();
    foreach( $regions as $region )
    {
        $timezones = array_merge( $timezones, DateTimeZone::listIdentifiers( $region ) );
    }

    $timezone_offsets = array();
    foreach( $timezones as $timezone )
    {
        $tz = new DateTimeZone($timezone);
        $timezone_offsets[$timezone] = $tz->getOffset(new DateTime);
    }

    // sort timezone by offset
    asort($timezone_offsets);

    $timezone_list = array();
    foreach( $timezone_offsets as $timezone => $offset )
    {
        $offset_prefix = $offset < 0 ? '-' : '+';
        $offset_formatted = gmdate( 'H:i', abs($offset) );

        $pretty_offset = "UTC${offset_prefix}${offset_formatted}";

        $timezone_list[$timezone] = "(${pretty_offset}) $timezone";
    }

    return $timezone_list;
}

Questo genererà un array simile a:

[Pacific/Midway] => (UTC-11:00) Pacific/Midway
[Pacific/Pago_Pago] => (UTC-11:00) Pacific/Pago_Pago
[Pacific/Niue] => (UTC-11:00) Pacific/Niue
[Pacific/Honolulu] => (UTC-10:00) Pacific/Honolulu
[Pacific/Fakaofo] => (UTC-10:00) Pacific/Fakaofo
…

Attualmente è ordinato in base agli offset, ma puoi facilmente ordinare in base al nome del fuso orario facendo ksort()invece di asort().

Nonostante il numero di risposte esistenti, ho fatto l'ennesima soluzione a questo problema. I pro della mia implementazione sono:

• L'elenco dei fusi orari viene generato in modo dinamico e quindi si aggiorna automaticamente quando i fusi orari potrebbero cambiare (in PHP).
• I nomi del fuso orario sono preimpostati. Ad esempio, "America / St_Barthelemy" diventa "America, St. Barthelemy".
• I fusi orari sono ordinati per offset e nome. La risposta di Toland ordina solo sull'offset, risultando in gruppi di fusi orari non ordinati all'interno dello stesso offset.
• Le informazioni di offset non vengono recuperate dal DateTimeZone::listAbbreviationsmomento che quel metodo restituisce anche informazioni storiche sul fuso orario . La risposta di Favio utilizza questo metodo, che si traduce in offset (storici) errati
• L'elenco dei fusi orari viene generato solo quando richiesto per la prima volta (e "memorizzato nella cache" utilizzando una variabile statica).

Ecco il codice completo:

function timezone_list() {
    static $timezones = null;

    if ($timezones === null) {
        $timezones = [];
        $offsets = [];
        $now = new DateTime('now', new DateTimeZone('UTC'));

        foreach (DateTimeZone::listIdentifiers() as $timezone) {
            $now->setTimezone(new DateTimeZone($timezone));
            $offsets[] = $offset = $now->getOffset();
            $timezones[$timezone] = '(' . format_GMT_offset($offset) . ') ' . format_timezone_name($timezone);
        }

        array_multisort($offsets, $timezones);
    }

    return $timezones;
}

function format_GMT_offset($offset) {
    $hours = intval($offset / 3600);
    $minutes = abs(intval($offset % 3600 / 60));
    return 'GMT' . ($offset ? sprintf('%+03d:%02d', $hours, $minutes) : '');
}

function format_timezone_name($name) {
    $name = str_replace('/', ', ', $name);
    $name = str_replace('_', ' ', $name);
    $name = str_replace('St ', 'St. ', $name);
    return $name;
}

Ed ecco un esempio dell'output

Array
(
    [Pacific/Midway]    => (GMT-11:00) Pacific, Midway
    [Pacific/Niue]      => (GMT-11:00) Pacific, Niue
    [Pacific/Pago_Pago] => (GMT-11:00) Pacific, Pago Pago
    [America/Adak]      => (GMT-10:00) America, Adak
    [Pacific/Honolulu]  => (GMT-10:00) Pacific, Honolulu
    [Pacific/Johnston]  => (GMT-10:00) Pacific, Johnston
    [Pacific/Rarotonga] => (GMT-10:00) Pacific, Rarotonga
    [Pacific/Tahiti]    => (GMT-10:00) Pacific, Tahiti
    [Pacific/Marquesas] => (GMT-09:30) Pacific, Marquesas
    [America/Anchorage] => (GMT-09:00) America, Anchorage
    ...
)

Lo farei con il seguente codice che è simile alla risposta accettata (sono consapevole che il codice potrebbe essere refactored :)):

    $list = DateTimeZone::listAbbreviations();
    $idents = DateTimeZone::listIdentifiers();

    $data = $offset = $added = array();
    foreach ($list as $abbr => $info) {
        foreach ($info as $zone) {
            if ( ! empty($zone['timezone_id'])
                AND
                ! in_array($zone['timezone_id'], $added)
                AND 
                  in_array($zone['timezone_id'], $idents)) {
                $z = new DateTimeZone($zone['timezone_id']);
                $c = new DateTime(null, $z);
                $zone['time'] = $c->format('H:i a');
                $offset[] = $zone['offset'] = $z->getOffset($c);
                $data[] = $zone;
                $added[] = $zone['timezone_id'];
            }
        }
    }

    array_multisort($offset, SORT_ASC, $data);
    $options = array();
    foreach ($data as $key => $row) {
        $options[$row['timezone_id']] = $row['time'] . ' - '
                                        . formatOffset($row['offset']) 
                                        . ' ' . $row['timezone_id'];
    }

    // now you can use $options;

function formatOffset($offset) {
        $hours = $offset / 3600;
        $remainder = $offset % 3600;
        $sign = $hours > 0 ? '+' : '-';
        $hour = (int) abs($hours);
        $minutes = (int) abs($remainder / 60);

        if ($hour == 0 AND $minutes == 0) {
            $sign = ' ';
        }
        return 'GMT' . $sign . str_pad($hour, 2, '0', STR_PAD_LEFT) 
                .':'. str_pad($minutes,2, '0');

}

Produce qualcosa del tipo:

<option value="America/Boise" label="02:10 am - GMT-06:00 America/Boise">02:10 am - GMT-06:00 America/Boise</option>

<option value="America/Denver" label="02:10 am - GMT-06:00 America/Denver">02:10 am - GMT-06:00 America/Denver</option>
<option value="America/Edmonton" label="02:10 am - GMT-06:00 America/Edmonton">02:10 am - GMT-06:00 America/Edmonton</option>
<option value="America/Inuvik" label="02:10 am - GMT-06:00 America/Inuvik">02:10 am - GMT-06:00 America/Inuvik</option>
<option value="America/Shiprock" label="02:10 am - GMT-06:00 America/Shiprock">02:10 am - GMT-06:00 America/Shiprock</option>

<option value="America/Belize" label="02:10 am - GMT-05:00 America/Belize">02:10 am - GMT-05:00 America/Belize</option>

Spero che ti aiuti un po 'e / o ti ispiri a venire con qualcosa di meglio.

È possibile creare un menu a discesa molto semplice da questo array (è stato un compito dispendioso in termini di tempo per metterlo insieme e testarlo). Usiamo già questo elenco in alcune delle nostre app.

È molto importante memorizzare gli identificatori del fuso orario nel database e non solo l'offset del fuso orario come "GMT + 2", a causa dell'ora legale.

AGGIORNARE

Ho aggiornato / corretto l'elenco dei fusi orari (anche checkout: https://github.com/paptamas/timezones ):

<?php
$timezones = array (
'(GMT-11:00) Midway Island' => 'Pacific/Midway',
'(GMT-11:00) Samoa' => 'Pacific/Samoa',
'(GMT-10:00) Hawaii' => 'Pacific/Honolulu',
'(GMT-09:00) Alaska' => 'US/Alaska',
'(GMT-08:00) Pacific Time (US &amp; Canada)' => 'America/Los_Angeles',
'(GMT-08:00) Tijuana' => 'America/Tijuana',
'(GMT-07:00) Arizona' => 'US/Arizona',
'(GMT-07:00) Chihuahua' => 'America/Chihuahua',
'(GMT-07:00) La Paz' => 'America/Chihuahua',
'(GMT-07:00) Mazatlan' => 'America/Mazatlan',
'(GMT-07:00) Mountain Time (US &amp; Canada)' => 'US/Mountain',
'(GMT-06:00) Central America' => 'America/Managua',
'(GMT-06:00) Central Time (US &amp; Canada)' => 'US/Central',
'(GMT-06:00) Guadalajara' => 'America/Mexico_City',
'(GMT-06:00) Mexico City' => 'America/Mexico_City',
'(GMT-06:00) Monterrey' => 'America/Monterrey',
'(GMT-06:00) Saskatchewan' => 'Canada/Saskatchewan',
'(GMT-05:00) Bogota' => 'America/Bogota',
'(GMT-05:00) Eastern Time (US &amp; Canada)' => 'US/Eastern',
'(GMT-05:00) Indiana (East)' => 'US/East-Indiana',
'(GMT-05:00) Lima' => 'America/Lima',
'(GMT-05:00) Quito' => 'America/Bogota',
'(GMT-04:00) Atlantic Time (Canada)' => 'Canada/Atlantic',
'(GMT-04:30) Caracas' => 'America/Caracas',
'(GMT-04:00) La Paz' => 'America/La_Paz',
'(GMT-04:00) Santiago' => 'America/Santiago',
'(GMT-03:30) Newfoundland' => 'Canada/Newfoundland',
'(GMT-03:00) Brasilia' => 'America/Sao_Paulo',
'(GMT-03:00) Buenos Aires' => 'America/Argentina/Buenos_Aires',
'(GMT-03:00) Georgetown' => 'America/Argentina/Buenos_Aires',
'(GMT-03:00) Greenland' => 'America/Godthab',
'(GMT-02:00) Mid-Atlantic' => 'America/Noronha',
'(GMT-01:00) Azores' => 'Atlantic/Azores',
'(GMT-01:00) Cape Verde Is.' => 'Atlantic/Cape_Verde',
'(GMT+00:00) Casablanca' => 'Africa/Casablanca',
'(GMT+00:00) Edinburgh' => 'Europe/London',
'(GMT+00:00) Greenwich Mean Time : Dublin' => 'Etc/Greenwich',
'(GMT+00:00) Lisbon' => 'Europe/Lisbon',
'(GMT+00:00) London' => 'Europe/London',
'(GMT+00:00) Monrovia' => 'Africa/Monrovia',
'(GMT+00:00) UTC' => 'UTC',
'(GMT+01:00) Amsterdam' => 'Europe/Amsterdam',
'(GMT+01:00) Belgrade' => 'Europe/Belgrade',
'(GMT+01:00) Berlin' => 'Europe/Berlin',
'(GMT+01:00) Bern' => 'Europe/Berlin',
'(GMT+01:00) Bratislava' => 'Europe/Bratislava',
'(GMT+01:00) Brussels' => 'Europe/Brussels',
'(GMT+01:00) Budapest' => 'Europe/Budapest',
'(GMT+01:00) Copenhagen' => 'Europe/Copenhagen',
'(GMT+01:00) Ljubljana' => 'Europe/Ljubljana',
'(GMT+01:00) Madrid' => 'Europe/Madrid',
'(GMT+01:00) Paris' => 'Europe/Paris',
'(GMT+01:00) Prague' => 'Europe/Prague',
'(GMT+01:00) Rome' => 'Europe/Rome',
'(GMT+01:00) Sarajevo' => 'Europe/Sarajevo',
'(GMT+01:00) Skopje' => 'Europe/Skopje',
'(GMT+01:00) Stockholm' => 'Europe/Stockholm',
'(GMT+01:00) Vienna' => 'Europe/Vienna',
'(GMT+01:00) Warsaw' => 'Europe/Warsaw',
'(GMT+01:00) West Central Africa' => 'Africa/Lagos',
'(GMT+01:00) Zagreb' => 'Europe/Zagreb',
'(GMT+02:00) Athens' => 'Europe/Athens',
'(GMT+02:00) Bucharest' => 'Europe/Bucharest',
'(GMT+02:00) Cairo' => 'Africa/Cairo',
'(GMT+02:00) Harare' => 'Africa/Harare',
'(GMT+02:00) Helsinki' => 'Europe/Helsinki',
'(GMT+02:00) Istanbul' => 'Europe/Istanbul',
'(GMT+02:00) Jerusalem' => 'Asia/Jerusalem',
'(GMT+02:00) Kyiv' => 'Europe/Helsinki',
'(GMT+02:00) Pretoria' => 'Africa/Johannesburg',
'(GMT+02:00) Riga' => 'Europe/Riga',
'(GMT+02:00) Sofia' => 'Europe/Sofia',
'(GMT+02:00) Tallinn' => 'Europe/Tallinn',
'(GMT+02:00) Vilnius' => 'Europe/Vilnius',
'(GMT+03:00) Baghdad' => 'Asia/Baghdad',
'(GMT+03:00) Kuwait' => 'Asia/Kuwait',
'(GMT+03:00) Minsk' => 'Europe/Minsk',
'(GMT+03:00) Nairobi' => 'Africa/Nairobi',
'(GMT+03:00) Riyadh' => 'Asia/Riyadh',
'(GMT+03:00) Volgograd' => 'Europe/Volgograd',
'(GMT+03:30) Tehran' => 'Asia/Tehran',
'(GMT+04:00) Abu Dhabi' => 'Asia/Muscat',
'(GMT+04:00) Baku' => 'Asia/Baku',
'(GMT+04:00) Moscow' => 'Europe/Moscow',
'(GMT+04:00) Muscat' => 'Asia/Muscat',
'(GMT+04:00) St. Petersburg' => 'Europe/Moscow',
'(GMT+04:00) Tbilisi' => 'Asia/Tbilisi',
'(GMT+04:00) Yerevan' => 'Asia/Yerevan',
'(GMT+04:30) Kabul' => 'Asia/Kabul',
'(GMT+05:00) Islamabad' => 'Asia/Karachi',
'(GMT+05:00) Karachi' => 'Asia/Karachi',
'(GMT+05:00) Tashkent' => 'Asia/Tashkent',
'(GMT+05:30) Chennai' => 'Asia/Calcutta',
'(GMT+05:30) Kolkata' => 'Asia/Kolkata',
'(GMT+05:30) Mumbai' => 'Asia/Calcutta',
'(GMT+05:30) New Delhi' => 'Asia/Calcutta',
'(GMT+05:30) Sri Jayawardenepura' => 'Asia/Calcutta',
'(GMT+05:45) Kathmandu' => 'Asia/Katmandu',
'(GMT+06:00) Almaty' => 'Asia/Almaty',
'(GMT+06:00) Astana' => 'Asia/Dhaka',
'(GMT+06:00) Dhaka' => 'Asia/Dhaka',
'(GMT+06:00) Ekaterinburg' => 'Asia/Yekaterinburg',
'(GMT+06:30) Rangoon' => 'Asia/Rangoon',
'(GMT+07:00) Bangkok' => 'Asia/Bangkok',
'(GMT+07:00) Hanoi' => 'Asia/Bangkok',
'(GMT+07:00) Jakarta' => 'Asia/Jakarta',
'(GMT+07:00) Novosibirsk' => 'Asia/Novosibirsk',
'(GMT+08:00) Beijing' => 'Asia/Hong_Kong',
'(GMT+08:00) Chongqing' => 'Asia/Chongqing',
'(GMT+08:00) Hong Kong' => 'Asia/Hong_Kong',
'(GMT+08:00) Krasnoyarsk' => 'Asia/Krasnoyarsk',
'(GMT+08:00) Kuala Lumpur' => 'Asia/Kuala_Lumpur',
'(GMT+08:00) Perth' => 'Australia/Perth',
'(GMT+08:00) Singapore' => 'Asia/Singapore',
'(GMT+08:00) Taipei' => 'Asia/Taipei',
'(GMT+08:00) Ulaan Bataar' => 'Asia/Ulan_Bator',
'(GMT+08:00) Urumqi' => 'Asia/Urumqi',
'(GMT+09:00) Irkutsk' => 'Asia/Irkutsk',
'(GMT+09:00) Osaka' => 'Asia/Tokyo',
'(GMT+09:00) Sapporo' => 'Asia/Tokyo',
'(GMT+09:00) Seoul' => 'Asia/Seoul',
'(GMT+09:00) Tokyo' => 'Asia/Tokyo',
'(GMT+09:30) Adelaide' => 'Australia/Adelaide',
'(GMT+09:30) Darwin' => 'Australia/Darwin',
'(GMT+10:00) Brisbane' => 'Australia/Brisbane',
'(GMT+10:00) Canberra' => 'Australia/Canberra',
'(GMT+10:00) Guam' => 'Pacific/Guam',
'(GMT+10:00) Hobart' => 'Australia/Hobart',
'(GMT+10:00) Melbourne' => 'Australia/Melbourne',
'(GMT+10:00) Port Moresby' => 'Pacific/Port_Moresby',
'(GMT+10:00) Sydney' => 'Australia/Sydney',
'(GMT+10:00) Yakutsk' => 'Asia/Yakutsk',
'(GMT+11:00) Vladivostok' => 'Asia/Vladivostok',
'(GMT+12:00) Auckland' => 'Pacific/Auckland',
'(GMT+12:00) Fiji' => 'Pacific/Fiji',
'(GMT+12:00) International Date Line West' => 'Pacific/Kwajalein',
'(GMT+12:00) Kamchatka' => 'Asia/Kamchatka',
'(GMT+12:00) Magadan' => 'Asia/Magadan',
'(GMT+12:00) Marshall Is.' => 'Pacific/Fiji',
'(GMT+12:00) New Caledonia' => 'Asia/Magadan',
'(GMT+12:00) Solomon Is.' => 'Asia/Magadan',
'(GMT+12:00) Wellington' => 'Pacific/Auckland',
'(GMT+13:00) Nuku\'alofa' => 'Pacific/Tongatapu'
);
?>   

Modifica la risposta di Tamas per rimuovere tutte le "altre" voci che il sito php.net afferma non dovrebbero più essere utilizzate.

Forse non importa, ma solo seguendo le migliori pratiche. Vedi l'avviso in fondo a: http://fr2.php.net/manual/en/timezones.others.php

Inoltre, sebbene questo elenco abbia le Azzorre come GMT -1, in effetti penso che sia lo stesso (almeno a volte) del GMT, ma non ne sono sicuro.

Modifica per offrire questo in sql in modo da poter creare l'elenco a discesa in un modulo e far sì che la risposta dell'utente sia legata a un indice.

Modifica di nuovo per rimuovere lo spazio iniziale

CREATE TABLE IF NOT EXISTS `timezones` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(44) DEFAULT NULL,
  `timezone` varchar(30) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=utf8 AUTO_INCREMENT=141 ;

--
-- Dumping data for table `timezones`
--

INSERT INTO `timezones` (`id`, `name`, `timezone`) VALUES
(1, '(GMT-11:00) Midway Island ', 'Pacific/Midway'),
(2, '(GMT-11:00) Samoa ', 'Pacific/Samoa'),
(3, '(GMT-10:00) Hawaii ', 'Pacific/Honolulu'),
(4, '(GMT-09:00) Alaska ', 'America/Anchorage'),
(5, '(GMT-08:00) Pacific Time (US & Canada) ', 'America/Los_Angeles'),
(6, '(GMT-08:00) Tijuana ', 'America/Tijuana'),
(7, '(GMT-07:00) Chihuahua ', 'America/Chihuahua'),
(8, '(GMT-07:00) La Paz ', 'America/Chihuahua'),
(9, '(GMT-07:00) Mazatlan ', 'America/Mazatlan'),
(10, '(GMT-07:00) Mountain Time (US & Canada) ', 'America/Denver'),
(11, '(GMT-06:00) Central America ', 'America/Managua'),
(12, '(GMT-06:00) Central Time (US & Canada) ', 'America/Chicago'),
(13, '(GMT-06:00) Guadalajara ', 'America/Mexico_City'),
(14, '(GMT-06:00) Mexico City ', 'America/Mexico_City'),
(15, '(GMT-06:00) Monterrey ', 'America/Monterrey'),
(16, '(GMT-05:00) Bogota ', 'America/Bogota'),
(17, '(GMT-05:00) Eastern Time (US & Canada) ', 'America/New_York'),
(18, '(GMT-05:00) Lima ', 'America/Lima'),
(19, '(GMT-05:00) Quito ', 'America/Bogota'),
(20, '(GMT-04:00) Atlantic Time (Canada) ', 'Canada/Atlantic'),
(21, '(GMT-04:30) Caracas ', 'America/Caracas'),
(22, '(GMT-04:00) La Paz ', 'America/La_Paz'),
(23, '(GMT-04:00) Santiago ', 'America/Santiago'),
(24, '(GMT-03:30) Newfoundland ', 'America/St_Johns'),
(25, '(GMT-03:00) Brasilia ', 'America/Sao_Paulo'),
(26, '(GMT-03:00) Buenos Aires ', 'America/Argentina/Buenos_Aires'),
(27, '(GMT-03:00) Georgetown ', 'America/Argentina/Buenos_Aires'),
(28, '(GMT-03:00) Greenland ', 'America/Godthab'),
(29, '(GMT-02:00) Mid-Atlantic ', 'America/Noronha'),
(30, '(GMT-01:00) Azores ', 'Atlantic/Azores'),
(31, '(GMT-01:00) Cape Verde Is. ', 'Atlantic/Cape_Verde'),
(32, '(GMT+00:00) Casablanca ', 'Africa/Casablanca'),
(33, '(GMT+00:00) Edinburgh ', 'Europe/London'),
(34, '(GMT+00:00) Dublin ', 'Europe/Dublin'),
(35, '(GMT+00:00) Lisbon ', 'Europe/Lisbon'),
(36, '(GMT+00:00) London ', 'Europe/London'),
(37, '(GMT+00:00) Monrovia ', 'Africa/Monrovia'),
(38, '(GMT+00:00) UTC ', 'UTC'),
(39, '(GMT+01:00) Amsterdam ', 'Europe/Amsterdam'),
(40, '(GMT+01:00) Belgrade ', 'Europe/Belgrade'),
(41, '(GMT+01:00) Berlin ', 'Europe/Berlin'),
(42, '(GMT+01:00) Bern ', 'Europe/Berlin'),
(43, '(GMT+01:00) Bratislava ', 'Europe/Bratislava'),
(44, '(GMT+01:00) Brussels ', 'Europe/Brussels'),
(45, '(GMT+01:00) Budapest ', 'Europe/Budapest'),
(46, '(GMT+01:00) Copenhagen ', 'Europe/Copenhagen'),
(47, '(GMT+01:00) Ljubljana ', 'Europe/Ljubljana'),
(48, '(GMT+01:00) Madrid ', 'Europe/Madrid'),
(49, '(GMT+01:00) Paris ', 'Europe/Paris'),
(50, '(GMT+01:00) Prague ', 'Europe/Prague'),
(51, '(GMT+01:00) Rome ', 'Europe/Rome'),
(52, '(GMT+01:00) Sarajevo ', 'Europe/Sarajevo'),
(53, '(GMT+01:00) Skopje ', 'Europe/Skopje'),
(54, '(GMT+01:00) Stockholm ', 'Europe/Stockholm'),
(55, '(GMT+01:00) Vienna ', 'Europe/Vienna'),
(56, '(GMT+01:00) Warsaw ', 'Europe/Warsaw'),
(57, '(GMT+01:00) West Central Africa ', 'Africa/Lagos'),
(58, '(GMT+01:00) Zagreb ', 'Europe/Zagreb'),
(59, '(GMT+02:00) Athens ', 'Europe/Athens'),
(60, '(GMT+02:00) Bucharest ', 'Europe/Bucharest'),
(61, '(GMT+02:00) Cairo ', 'Africa/Cairo'),
(62, '(GMT+02:00) Harare ', 'Africa/Harare'),
(63, '(GMT+02:00) Helsinki ', 'Europe/Helsinki'),
(64, '(GMT+02:00) Istanbul ', 'Europe/Istanbul'),
(65, '(GMT+02:00) Jerusalem ', 'Asia/Jerusalem'),
(66, '(GMT+02:00) Kyiv ', 'Europe/Helsinki'),
(67, '(GMT+02:00) Pretoria ', 'Africa/Johannesburg'),
(68, '(GMT+02:00) Riga ', 'Europe/Riga'),
(69, '(GMT+02:00) Sofia ', 'Europe/Sofia'),
(70, '(GMT+02:00) Tallinn ', 'Europe/Tallinn'),
(71, '(GMT+02:00) Vilnius ', 'Europe/Vilnius'),
(72, '(GMT+03:00) Baghdad ', 'Asia/Baghdad'),
(73, '(GMT+03:00) Kuwait ', 'Asia/Kuwait'),
(74, '(GMT+03:00) Minsk ', 'Europe/Minsk'),
(75, '(GMT+03:00) Nairobi ', 'Africa/Nairobi'),
(76, '(GMT+03:00) Riyadh ', 'Asia/Riyadh'),
(77, '(GMT+03:00) Volgograd ', 'Europe/Volgograd'),
(78, '(GMT+03:30) Tehran ', 'Asia/Tehran'),
(79, '(GMT+04:00) Abu Dhabi ', 'Asia/Muscat'),
(80, '(GMT+04:00) Baku ', 'Asia/Baku'),
(81, '(GMT+04:00) Moscow ', 'Europe/Moscow'),
(82, '(GMT+04:00) Muscat ', 'Asia/Muscat'),
(83, '(GMT+04:00) St. Petersburg ', 'Europe/Moscow'),
(84, '(GMT+04:00) Tbilisi ', 'Asia/Tbilisi'),
(85, '(GMT+04:00) Yerevan ', 'Asia/Yerevan'),
(86, '(GMT+04:30) Kabul ', 'Asia/Kabul'),
(87, '(GMT+05:00) Islamabad ', 'Asia/Karachi'),
(88, '(GMT+05:00) Karachi ', 'Asia/Karachi'),
(89, '(GMT+05:00) Tashkent ', 'Asia/Tashkent'),
(90, '(GMT+05:30) Chennai ', 'Asia/Calcutta'),
(91, '(GMT+05:30) Kolkata ', 'Asia/Kolkata'),
(92, '(GMT+05:30) Mumbai ', 'Asia/Calcutta'),
(93, '(GMT+05:30) New Delhi ', 'Asia/Calcutta'),
(94, '(GMT+05:30) Sri Jayawardenepura ', 'Asia/Calcutta'),
(95, '(GMT+05:45) Kathmandu ', 'Asia/Katmandu'),
(96, '(GMT+06:00) Almaty ', 'Asia/Almaty'),
(97, '(GMT+06:00) Astana ', 'Asia/Dhaka'),
(98, '(GMT+06:00) Dhaka ', 'Asia/Dhaka'),
(99, '(GMT+06:00) Ekaterinburg ', 'Asia/Yekaterinburg'),
(100, '(GMT+06:30) Rangoon ', 'Asia/Rangoon'),
(101, '(GMT+07:00) Bangkok ', 'Asia/Bangkok'),
(102, '(GMT+07:00) Hanoi ', 'Asia/Bangkok'),
(103, '(GMT+07:00) Jakarta ', 'Asia/Jakarta'),
(104, '(GMT+07:00) Novosibirsk ', 'Asia/Novosibirsk'),
(105, '(GMT+08:00) Beijing ', 'Asia/Hong_Kong'),
(106, '(GMT+08:00) Chongqing ', 'Asia/Chongqing'),
(107, '(GMT+08:00) Hong Kong ', 'Asia/Hong_Kong'),
(108, '(GMT+08:00) Krasnoyarsk ', 'Asia/Krasnoyarsk'),
(109, '(GMT+08:00) Kuala Lumpur ', 'Asia/Kuala_Lumpur'),
(110, '(GMT+08:00) Perth ', 'Australia/Perth'),
(111, '(GMT+08:00) Singapore ', 'Asia/Singapore'),
(112, '(GMT+08:00) Taipei ', 'Asia/Taipei'),
(113, '(GMT+08:00) Ulaan Bataar ', 'Asia/Ulan_Bator'),
(114, '(GMT+08:00) Urumqi ', 'Asia/Urumqi'),
(115, '(GMT+09:00) Irkutsk ', 'Asia/Irkutsk'),
(116, '(GMT+09:00) Osaka ', 'Asia/Tokyo'),
(117, '(GMT+09:00) Sapporo ', 'Asia/Tokyo'),
(118, '(GMT+09:00) Seoul ', 'Asia/Seoul'),
(119, '(GMT+09:00) Tokyo ', 'Asia/Tokyo'),
(120, '(GMT+09:30) Adelaide ', 'Australia/Adelaide'),
(121, '(GMT+09:30) Darwin ', 'Australia/Darwin'),
(122, '(GMT+10:00) Brisbane ', 'Australia/Brisbane'),
(123, '(GMT+10:00) Canberra ', 'Australia/Canberra'),
(124, '(GMT+10:00) Guam ', 'Pacific/Guam'),
(125, '(GMT+10:00) Hobart ', 'Australia/Hobart'),
(126, '(GMT+10:00) Melbourne ', 'Australia/Melbourne'),
(127, '(GMT+10:00) Port Moresby ', 'Pacific/Port_Moresby'),
(128, '(GMT+10:00) Sydney ', 'Australia/Sydney'),
(129, '(GMT+10:00) Yakutsk ', 'Asia/Yakutsk'),
(130, '(GMT+11:00) Vladivostok ', 'Asia/Vladivostok'),
(131, '(GMT+12:00) Auckland ', 'Pacific/Auckland'),
(132, '(GMT+12:00) Fiji ', 'Pacific/Fiji'),
(133, '(GMT+12:00) International Date Line West ', 'Pacific/Kwajalein'),
(134, '(GMT+12:00) Kamchatka ', 'Asia/Kamchatka'),
(135, '(GMT+12:00) Magadan ', 'Asia/Magadan'),
(136, '(GMT+12:00) Marshall Is. ', 'Pacific/Fiji'),
(137, '(GMT+12:00) New Caledonia ', 'Asia/Magadan'),
(138, '(GMT+12:00) Solomon Is. ', 'Asia/Magadan'),
(139, '(GMT+12:00) Wellington ', 'Pacific/Auckland'),
(140, '(GMT+13:00) Nuku\\alofa ', 'Pacific/Tongatapu');

/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;
/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;
/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;

Eccone uno che crea un array multidimensionale ordinato per offset e nome niceified:

function timezones() {
    $timezones = [];

    foreach (timezone_identifiers_list() as $timezone) {
        $datetime = new \DateTime('now', new DateTimeZone($timezone));
        $timezones[] = [
            'sort' => str_replace(':', '', $datetime->format('P')),
            'offset' => $datetime->format('P'),
            'name' => str_replace('_', ' ', implode(', ', explode('/', $timezone))),
            'timezone' => $timezone,
        ];
    }

    usort($timezones, function($a, $b) {
        return $a['sort'] - $b['sort'] ?: strcmp($a['name'], $b['name']);
    });

    return $timezones;
}

foreach (timezones() as $timezone) {
    echo '(UTC '.$timezone['offset'].') '.$timezone['name'].'<br>';
}

Echos:

(UTC -11:00) Pacific, Midway
(UTC -11:00) Pacific, Niue
(UTC -11:00) Pacific, Pago Pago
(UTC -10:00) Pacific, Honolulu
(UTC -10:00) Pacific, Johnston
(UTC -10:00) Pacific, Rarotonga
(UTC -10:00) Pacific, Tahiti
(UTC -09:30) Pacific, Marquesas
(UTC -09:00) America, Adak
(UTC -09:00) Pacific, Gambier
(UTC -08:00) America, Anchorage
(UTC -08:00) America, Juneau
...

$timezone = array(
    'Pacific/Midway' => '(GMT-11:00) Midway Island, Samoa',
    'America/Adak' => '(GMT-10:00) Hawaii-Aleutian',
    'Etc/GMT+10' => '(GMT-10:00) Hawaii',
    'Pacific/Marquesas' => '(GMT-09:30) Marquesas Islands',
    'Pacific/Gambier' => '(GMT-09:00) Gambier Islands',
    'America/Anchorage' => '(GMT-09:00) Alaska',
    'America/Ensenada' => '(GMT-08:00) Tijuana, Baja California',
    'Etc/GMT+8' => '(GMT-08:00) Pitcairn Islands',
    'America/Los_Angeles' => '(GMT-08:00) Pacific Time (US & Canada)',
    'America/Denver' => '(GMT-07:00) Mountain Time (US & Canada)',
    'America/Chihuahua' => '(GMT-07:00) Chihuahua, La Paz, Mazatlan',
    'America/Dawson_Creek' => '(GMT-07:00) Arizona',
    'America/Belize' => '(GMT-06:00) Saskatchewan, Central America',
    'America/Cancun' => '(GMT-06:00) Guadalajara, Mexico City, Monterrey',
    'Chile/EasterIsland' => '(GMT-06:00) Easter Island',
    'America/Chicago' => '(GMT-06:00) Central Time (US & Canada)',
    'America/New_York' => '(GMT-05:00) Eastern Time (US & Canada)',
    'America/Havana' => '(GMT-05:00) Cuba',
    'America/Bogota' => '(GMT-05:00) Bogota, Lima, Quito, Rio Branco',
    'America/Caracas' => '(GMT-04:30) Caracas',
    'America/Santiago' => '(GMT-04:00) Santiago',
    'America/La_Paz' => '(GMT-04:00) La Paz',
    'Atlantic/Stanley' => '(GMT-04:00) Faukland Islands',
    'America/Campo_Grande' => '(GMT-04:00) Brazil',
    'America/Goose_Bay' => '(GMT-04:00) Atlantic Time (Goose Bay)',
    'America/Glace_Bay' => '(GMT-04:00) Atlantic Time (Canada)',
    'America/St_Johns' => '(GMT-03:30) Newfoundland',
    'America/Araguaina' => '(GMT-03:00) UTC-3',
    'America/Montevideo' => '(GMT-03:00) Montevideo',
    'America/Miquelon' => '(GMT-03:00) Miquelon, St. Pierre',
    'America/Godthab' => '(GMT-03:00) Greenland',
    'America/Argentina/Buenos_Aires' => '(GMT-03:00) Buenos Aires',
    'America/Sao_Paulo' => '(GMT-03:00) Brasilia',
    'America/Noronha' => '(GMT-02:00) Mid-Atlantic',
    'Atlantic/Cape_Verde' => '(GMT-01:00) Cape Verde Is.',
    'Atlantic/Azores' => '(GMT-01:00) Azores',
    'Europe/Belfast' => '(GMT) Greenwich Mean Time : Belfast',
    'Europe/Dublin' => '(GMT) Greenwich Mean Time : Dublin',
    'Europe/Lisbon' => '(GMT) Greenwich Mean Time : Lisbon',
    'Europe/London' => '(GMT) Greenwich Mean Time : London',
    'Africa/Abidjan' => '(GMT) Monrovia, Reykjavik',
    'Europe/Amsterdam' => '(GMT+01:00) Amsterdam, Berlin, Bern, Rome, Stockholm, Vienna',
    'Europe/Belgrade' => '(GMT+01:00) Belgrade, Bratislava, Budapest, Ljubljana, Prague',
    'Europe/Brussels' => '(GMT+01:00) Brussels, Copenhagen, Madrid, Paris',
    'Africa/Algiers' => '(GMT+01:00) West Central Africa',
    'Africa/Windhoek' => '(GMT+01:00) Windhoek',
    'Asia/Beirut' => '(GMT+02:00) Beirut',
    'Africa/Cairo' => '(GMT+02:00) Cairo',
    'Asia/Gaza' => '(GMT+02:00) Gaza',
    'Africa/Blantyre' => '(GMT+02:00) Harare, Pretoria',
    'Asia/Jerusalem' => '(GMT+02:00) Jerusalem',
    'Europe/Minsk' => '(GMT+02:00) Minsk',
    'Asia/Damascus' => '(GMT+02:00) Syria',
    'Europe/Moscow' => '(GMT+03:00) Moscow, St. Petersburg, Volgograd',
    'Africa/Addis_Ababa' => '(GMT+03:00) Nairobi',
    'Asia/Tehran' => '(GMT+03:30) Tehran',
    'Asia/Dubai' => '(GMT+04:00) Abu Dhabi, Muscat',
    'Asia/Yerevan' => '(GMT+04:00) Yerevan',
    'Asia/Kabul' => '(GMT+04:30) Kabul',
    'Asia/Yekaterinburg' => '(GMT+05:00) Ekaterinburg',
    'Asia/Tashkent' => '(GMT+05:00) Tashkent',
    'Asia/Kolkata' => '(GMT+05:30) Chennai, Kolkata, Mumbai, New Delhi',
    'Asia/Katmandu' => '(GMT+05:45) Kathmandu',
    'Asia/Dhaka' => '(GMT+06:00) Astana, Dhaka',
    'Asia/Novosibirsk' => '(GMT+06:00) Novosibirsk',
    'Asia/Rangoon' => '(GMT+06:30) Yangon (Rangoon)',
    'Asia/Bangkok' => '(GMT+07:00) Bangkok, Hanoi, Jakarta',
    'Asia/Krasnoyarsk' => '(GMT+07:00) Krasnoyarsk',
    'Asia/Hong_Kong' => '(GMT+08:00) Beijing, Chongqing, Hong Kong, Urumqi',
    'Asia/Irkutsk' => '(GMT+08:00) Irkutsk, Ulaan Bataar',
    'Australia/Perth' => '(GMT+08:00) Perth',
    'Australia/Eucla' => '(GMT+08:45) Eucla',
    'Asia/Tokyo' => '(GMT+09:00) Osaka, Sapporo, Tokyo',
    'Asia/Seoul' => '(GMT+09:00) Seoul',
    'Asia/Yakutsk' => '(GMT+09:00) Yakutsk',
    'Australia/Adelaide' => '(GMT+09:30) Adelaide',
    'Australia/Darwin' => '(GMT+09:30) Darwin',
    'Australia/Brisbane' => '(GMT+10:00) Brisbane',
    'Australia/Hobart' => '(GMT+10:00) Hobart',
    'Asia/Vladivostok' => '(GMT+10:00) Vladivostok',
    'Australia/Lord_Howe' => '(GMT+10:30) Lord Howe Island',
    'Etc/GMT-11' => '(GMT+11:00) Solomon Is., New Caledonia',
    'Asia/Magadan' => '(GMT+11:00) Magadan',
    'Pacific/Norfolk' => '(GMT+11:30) Norfolk Island',
    'Asia/Anadyr' => '(GMT+12:00) Anadyr, Kamchatka',
    'Pacific/Auckland' => '(GMT+12:00) Auckland, Wellington',
    'Etc/GMT-12' => '(GMT+12:00) Fiji, Kamchatka, Marshall Is.',
    'Pacific/Chatham' => '(GMT+12:45) Chatham Islands',
    'Pacific/Tongatapu' => '(GMT+13:00) Nukualofa',
    'Pacific/Kiritimati' => '(GMT+14:00) Kiritimati',

date_default_timezone_set($timezone);

L'uso di listAbbreviations () non ha senso in quanto per ogni area restituisce tutti i diversi offset che sono stati storicamente utilizzati lì, non solo quelli attuali. La fonte di base corretta dell'elenco è sicuramente listIdentifiers ().

Genererei l'elenco solo una volta e lo salverei per evitare di generarlo per ogni richiesta. Potrei rinfrescarlo una volta al mese.

Inoltre, potrei mettere tutte le informazioni sui fusi orari in un js-script separato e generare l'elenco di selezione stesso sul lato client. Anche la js-script potrebbe essere memorizzata nella cache, i fusi orari non cambiano spesso.

Inoltre, utilizzando JavaScript sul lato client, puoi conoscere l'ora locale corrente e quindi puoi trovare le zone che hanno lo stesso orario ora (i minuti possono differire, quindi il confronto dovrebbe essere approssimativo) e visualizzarli nella parte superiore del elenco, quindi l'utente non deve scorrere tutti i 400 elementi. È inoltre possibile visualizzare le zone adiacenti (+/- 1 ora) seguenti.

So che questa ha già una risposta, ma ho visto l'opportunità di migliorare una delle risposte qui. Toland H ha pubblicato un ottimo codice che fa esattamente quello che la domanda stava ponendo. Di seguito è una versione abbreviata ed espandibile del codice di Toland H:

• La funzione posiziona tutto nei tag opzione per te. Fai eco a ciò che ritorna tra i tag selezionati.
• Miglioramento importante: l'elenco viene ordinato per primo per continente e organizzato in gruppi di opzioni in base ai continenti. Lo rende molto user friendly per i visitatori che scelgono il loro fuso orario.

function generate_timezone_list() {
static $allRegions = array(
DateTimeZone::AFRICA,
DateTimeZone::AMERICA,
DateTimeZone::ANTARCTICA,
DateTimeZone::ASIA,
DateTimeZone::ATLANTIC,
DateTimeZone::AUSTRALIA,
DateTimeZone::EUROPE,
DateTimeZone::INDIAN,
DateTimeZone::PACIFIC
);
// Makes it easier to create option groups next
$list = array ('AFRICA','AMERICA','ANTARCTICA','ASIA','ATLANTIC','AUSTRALIA','EUROPE','INDIAN','PACIFIC');
// Make array holding the regions (continents), they are arrays w/ all their cities
$region = array();
foreach ($allRegions as $area){
array_push ($region,DateTimeZone::listIdentifiers( $area ));
}   
$count = count ($region); $i = 0; $holder = '';
// Go through each region one by one, sorting and formatting it's cities
while ($i < $count){
$chunck = $region[$i];
// Create the region (continents) option group
$holder .= '<optgroup label="---------- '.$list[$i].' ----------">';
$timezone_offsets = array();
foreach( $chunck as $timezone ){
$tz = new DateTimeZone($timezone);
$timezone_offsets[$timezone] = $tz->getOffset(new DateTime);
}
asort ($timezone_offsets);
$timezone_list = array();
foreach ($timezone_offsets as $timezone => $offset){
$offset_prefix = $offset < 0 ? '-' : '+';
$offset_formatted = gmdate( 'H:i', abs($offset) );
$pretty_offset = "UTC ${offset_prefix}${offset_formatted}";
$timezone_list[$timezone] = "(${pretty_offset}) $timezone";     
}
// All the formatting is done, finish and move on to next region
foreach ($timezone_list as $key => $val){
$holder .= '<option value="'.$key.'">'.$val.'</option>';
}
$holder .= '</optgroup>';
++$i;
}
return $holder;
}
echo "<select>".generate_timezone_list()."</select>";

Quindi tutto ciò che devi fare è echeggiare ciò che viene restituito tra i tag di selezione HTML. Otterrai un elenco di selezione simile a questo:

----- AFRICA -----
(UTC +00:00) Africa/ city name
(UTC +01:00) Africa/ city name
(UTC +02:00) Africa/ city name
(UTC +02:00) Africa/ city name
----- AMERICA -----
(UTC -09:00) America/ city name
(UTC -07:00) America/ city name
(UTC +02:00) America/ city name
(UTC +05:00) America/ city name

E così via...

Questa funzione PHP fa il lavoro per te e restituisce un array:

function time_zonelist(){
    $return = array();
    $timezone_identifiers_list = timezone_identifiers_list();
    foreach($timezone_identifiers_list as $timezone_identifier){
        $date_time_zone = new DateTimeZone($timezone_identifier);
        $date_time = new DateTime('now', $date_time_zone);
        $hours = floor($date_time_zone->getOffset($date_time) / 3600);
        $mins = floor(($date_time_zone->getOffset($date_time) - ($hours*3600)) / 60);
        $hours = 'GMT' . ($hours < 0 ? $hours : '+'.$hours);
        $mins = ($mins > 0 ? $mins : '0'.$mins);
        $text = str_replace("_"," ",$timezone_identifier);
        $return[$timezone_identifier] = $text.' ('.$hours.':'.$mins.')';
    }
    return $return;
}

Questa funzione PHP restituisce un array di tutti i fusi orari esistenti, incluso Offset:

Usalo ad esempio in questo modo:

print_r(time_zonelist());

Volevo avere qualcosa di più semplice per i miei utenti, come fa Google.

$timezones = [
    "AF" => [
        "name" => "Afghanistan" 
    ],
    "AL" => [
        "name" => "Albania" 
    ],
    "DZ" => [
        "name" => "Algeria" 
    ],
    "AS" => [
        "name" => "American Samoa" 
    ],
    "AD" => [
        "name" => "Andorra" 
    ],
    "AQ" => [
        "name" => "Antarctica" 
    ],
    "AG" => [
        "name" => "Antigua & Barbuda" 
    ],
    "AR" => [
        "name" => "Argentina" 
    ],
    "AM" => [
        "name" => "Armenia" 
    ],
    "AU" => [
        "name" => "Australia" 
    ],
    "AT" => [
        "name" => "Austria" 
    ],
    "AZ" => [
        "name" => "Azerbaijan" 
    ],
    "BS" => [
        "name" => "Bahamas" 
    ],
    "BD" => [
        "name" => "Bangladesh" 
    ],
    "BB" => [
        "name" => "Barbados" 
    ],
    "BY" => [
        "name" => "Belarus" 
    ],
    "BE" => [
        "name" => "Belgium" 
    ],
    "BZ" => [
        "name" => "Belize" 
    ],
    "BM" => [
        "name" => "Bermuda" 
    ],
    "BT" => [
        "name" => "Bhutan" 
    ],
    "BO" => [
        "name" => "Bolivia" 
    ],
    "BA" => [
        "name" => "Bosnia & Herzegovina" 
    ],
    "BR" => [
        "name" => "Brazil" 
    ],
    "IO" => [
        "name" => "British Indian Ocean Territory" 
    ],
    "BN" => [
        "name" => "Brunei" 
    ],
    "BG" => [
        "name" => "Bulgaria" 
    ],
    "CA" => [
        "name" => "Canada" 
    ],
    "CV" => [
        "name" => "Cape Verde" 
    ],
    "KY" => [
        "name" => "Cayman Islands" 
    ],
    "TD" => [
        "name" => "Chad" 
    ],
    "CL" => [
        "name" => "Chile" 
    ],
    "CN" => [
        "name" => "China" 
    ],
    "CX" => [
        "name" => "Christmas Island" 
    ],
    "CC" => [
        "name" => "Cocos (Keeling) Islands" 
    ],
    "CO" => [
        "name" => "Colombia" 
    ],
    "CK" => [
        "name" => "Cook Islands" 
    ],
    "CR" => [
        "name" => "Costa Rica" 
    ],
    "CI" => [
        "name" => "Côte d’Ivoire" 
    ],
    "HR" => [
        "name" => "Croatia" 
    ],
    "CU" => [
        "name" => "Cuba" 
    ],
    "CW" => [
        "name" => "Curaçao" 
    ],
    "CY" => [
        "name" => "Cyprus" 
    ],
    "CZ" => [
        "name" => "Czech Republic" 
    ],
    "DK" => [
        "name" => "Denmark" 
    ],
    "DO" => [
        "name" => "Dominican Republic" 
    ],
    "EC" => [
        "name" => "Ecuador" 
    ],
    "EG" => [
        "name" => "Egypt" 
    ],
    "SV" => [
        "name" => "El Salvador" 
    ],
    "EE" => [
        "name" => "Estonia" 
    ],
    "FK" => [
        "name" => "Falkland Islands (Islas Malvinas)" 
    ],
    "FO" => [
        "name" => "Faroe Islands" 
    ],
    "FJ" => [
        "name" => "Fiji" 
    ],
    "FI" => [
        "name" => "Finland" 
    ],
    "FR" => [
        "name" => "France" 
    ],
    "GF" => [
        "name" => "French Guiana" 
    ],
    "PF" => [
        "name" => "French Polynesia" 
    ],
    "TF" => [
        "name" => "French Southern Territories" 
    ],
    "GE" => [
        "name" => "Georgia" 
    ],
    "DE" => [
        "name" => "Germany" 
    ],
    "GH" => [
        "name" => "Ghana" 
    ],
    "GI" => [
        "name" => "Gibraltar" 
    ],
    "GR" => [
        "name" => "Greece" 
    ],
    "GL" => [
        "name" => "Greenland" 
    ],
    "GU" => [
        "name" => "Guam" 
    ],
    "GT" => [
        "name" => "Guatemala" 
    ],
    "GW" => [
        "name" => "Guinea-Bissau" 
    ],
    "GY" => [
        "name" => "Guyana" 
    ],
    "HT" => [
        "name" => "Haiti" 
    ],
    "HN" => [
        "name" => "Honduras" 
    ],
    "HK" => [
        "name" => "Hong Kong" 
    ],
    "HU" => [
        "name" => "Hungary" 
    ],
    "IS" => [
        "name" => "Iceland" 
    ],
    "IN" => [
        "name" => "India" 
    ],
    "ID" => [
        "name" => "Indonesia" 
    ],
    "IR" => [
        "name" => "Iran" 
    ],
    "IQ" => [
        "name" => "Iraq" 
    ],
    "IE" => [
        "name" => "Ireland" 
    ],
    "IL" => [
        "name" => "Israel" 
    ],
    "IT" => [
        "name" => "Italy" 
    ],
    "JM" => [
        "name" => "Jamaica" 
    ],
    "JP" => [
        "name" => "Japan" 
    ],
    "JO" => [
        "name" => "Jordan" 
    ],
    "KZ" => [
        "name" => "Kazakhstan" 
    ],
    "KE" => [
        "name" => "Kenya" 
    ],
    "KI" => [
        "name" => "Kiribati" 
    ],
    "KG" => [
        "name" => "Kyrgyzstan" 
    ],
    "LV" => [
        "name" => "Latvia" 
    ],
    "LB" => [
        "name" => "Lebanon" 
    ],
    "LR" => [
        "name" => "Liberia" 
    ],
    "LY" => [
        "name" => "Libya" 
    ],
    "LT" => [
        "name" => "Lithuania" 
    ],
    "LU" => [
        "name" => "Luxembourg" 
    ],
    "MO" => [
        "name" => "Macau" 
    ],
    "MK" => [
        "name" => "Macedonia (FYROM)" 
    ],
    "MY" => [
        "name" => "Malaysia" 
    ],
    "MV" => [
        "name" => "Maldives" 
    ],
    "MT" => [
        "name" => "Malta" 
    ],
    "MH" => [
        "name" => "Marshall Islands" 
    ],
    "MQ" => [
        "name" => "Martinique" 
    ],
    "MU" => [
        "name" => "Mauritius" 
    ],
    "MX" => [
        "name" => "Mexico" 
    ],
    "FM" => [
        "name" => "Micronesia" 
    ],
    "MD" => [
        "name" => "Moldova" 
    ],
    "MC" => [
        "name" => "Monaco" 
    ],
    "MN" => [
        "name" => "Mongolia" 
    ],
    "MA" => [
        "name" => "Morocco" 
    ],
    "MZ" => [
        "name" => "Mozambique" 
    ],
    "MM" => [
        "name" => "Myanmar (Burma)" 
    ],
    "NA" => [
        "name" => "Namibia" 
    ],
    "NR" => [
        "name" => "Nauru" 
    ],
    "NP" => [
        "name" => "Nepal" 
    ],
    "NL" => [
        "name" => "Netherlands" 
    ],
    "NC" => [
        "name" => "New Caledonia" 
    ],
    "NZ" => [
        "name" => "New Zealand" 
    ],
    "NI" => [
        "name" => "Nicaragua" 
    ],
    "NG" => [
        "name" => "Nigeria" 
    ],
    "NU" => [
        "name" => "Niue" 
    ],
    "NF" => [
        "name" => "Norfolk Island" 
    ],
    "KP" => [
        "name" => "North Korea" 
    ],
    "MP" => [
        "name" => "Northern Mariana Islands" 
    ],
    "NO" => [
        "name" => "Norway" 
    ],
    "PK" => [
        "name" => "Pakistan" 
    ],
    "PW" => [
        "name" => "Palau" 
    ],
    "PS" => [
        "name" => "Palestine" 
    ],
    "PA" => [
        "name" => "Panama" 
    ],
    "PG" => [
        "name" => "Papua New Guinea" 
    ],
    "PY" => [
        "name" => "Paraguay" 
    ],
    "PE" => [
        "name" => "Peru" 
    ],
    "PH" => [
        "name" => "Philippines" 
    ],
    "PN" => [
        "name" => "Pitcairn Islands" 
    ],
    "PL" => [
        "name" => "Poland" 
    ],
    "PT" => [
        "name" => "Portugal" 
    ],
    "PR" => [
        "name" => "Puerto Rico" 
    ],
    "QA" => [
        "name" => "Qatar" 
    ],
    "RE" => [
        "name" => "Réunion" 
    ],
    "RO" => [
        "name" => "Romania" 
    ],
    "RU" => [
        "name" => "Russia" 
    ],
    "WS" => [
        "name" => "Samoa" 
    ],
    "SM" => [
        "name" => "San Marino" 
    ],
    "SA" => [
        "name" => "Saudi Arabia" 
    ],
    "RS" => [
        "name" => "Serbia" 
    ],
    "SC" => [
        "name" => "Seychelles" 
    ],
    "SG" => [
        "name" => "Singapore" 
    ],
    "SK" => [
        "name" => "Slovakia" 
    ],
    "SI" => [
        "name" => "Slovenia" 
    ],
    "SB" => [
        "name" => "Solomon Islands" 
    ],
    "ZA" => [
        "name" => "South Africa" 
    ],
    "GS" => [
        "name" => "South Georgia & South Sandwich Islands" 
    ],
    "KR" => [
        "name" => "South Korea" 
    ],
    "ES" => [
        "name" => "Spain" 
    ],
    "LK" => [
        "name" => "Sri Lanka" 
    ],
    "PM" => [
        "name" => "St. Pierre & Miquelon" 
    ],
    "SD" => [
        "name" => "Sudan" 
    ],
    "SR" => [
        "name" => "Suriname" 
    ],
    "SJ" => [
        "name" => "Svalbard & Jan Mayen" 
    ],
    "SE" => [
        "name" => "Sweden" 
    ],
    "CH" => [
        "name" => "Switzerland" 
    ],
    "SY" => [
        "name" => "Syria" 
    ],
    "TW" => [
        "name" => "Taiwan" 
    ],
    "TJ" => [
        "name" => "Tajikistan" 
    ],
    "TH" => [
        "name" => "Thailand" 
    ],
    "TL" => [
        "name" => "Timor-Leste" 
    ],
    "TK" => [
        "name" => "Tokelau" 
    ],
    "TO" => [
        "name" => "Tonga" 
    ],
    "TT" => [
        "name" => "Trinidad & Tobago" 
    ],
    "TN" => [
        "name" => "Tunisia" 
    ],
    "TR" => [
        "name" => "Turkey" 
    ],
    "TM" => [
        "name" => "Turkmenistan" 
    ],
    "TC" => [
        "name" => "Turks & Caicos Islands" 
    ],
    "TV" => [
        "name" => "Tuvalu" 
    ],
    "UM" => [
        "name" => "U.S. Outlying Islands" 
    ],
    "UA" => [
        "name" => "Ukraine" 
    ],
    "AE" => [
        "name" => "United Arab Emirates" 
    ],
    "GB" => [
        "name" => "United Kingdom" 
    ],
    "US" => [
        "name" => "United States" 
    ],
    "UY" => [
        "name" => "Uruguay" 
    ],
    "UZ" => [
        "name" => "Uzbekistan" 
    ],
    "VU" => [
        "name" => "Vanuatu" 
    ],
    "VA" => [
        "name" => "Vatican City" 
    ],
    "VE" => [
        "name" => "Venezuela" 
    ],
    "VN" => [
        "name" => "Vietnam" 
    ],
    "WF" => [
        "name" => "Wallis & Futuna" 
    ],
    "EH" => [
        "name" => "Western Sahara" 
    ],
];

// taken from Toland Hon's Answer
function prettyOffset($offset) {
    $offset_prefix = $offset < 0 ? '-' : '+';
    $offset_formatted = gmdate( 'H:i', abs($offset) );

    $pretty_offset = "UTC${offset_prefix}${offset_formatted}";

    return $pretty_offset;
}

foreach ($timezones as $k => $v) {
    $tz = DateTimeZone::listIdentifiers(DateTimeZone::PER_COUNTRY, $k);

    foreach ($tz as $value) {
        $t = new DateTimeZone($value);
        $offset = (new DateTime("now", $t))->getOffset();
        $timezones[$k]['timezones'][$value] = prettyOffset($offset);
    }   
}