A head scratcher for you.
I am grabbing geo IP data from IPInfoDB's API and it returns a timezone offset from UTC including DST (if currently reflected).
For example, I live in EST (-5) and currently it's DST, so the geo IP API returns (-04:00) as the offset.
This is wonderful since DST is a freaking headache. But to my surprise, it caused another headache.
I load this data in PHP to be passed via AJAX to the application. I would like to have the live local time of the IP address on the app.
I have that all set perfectly, but I am going crazy trying to figure out how to set the PHP timezone to match the offset so I can just grab the current hours date('H'); and minutes date('i'); to pass to via AJAX.
I am unsure if there is a specific function that can just give me the current hours and minutes based on that offset or if there is a practical way to set the timezone based on the offset (which will have DST already applied if is in effect).
I've been searching and searching Google to find an answer to this, but what I am doing is more specific since DST is already applied.
I found one function on PHP.net that seems to do the trick (it works for my timezone and returns the correct time) although for other timezones such as PST, it's returning 1 hour later than it should be even though the offset is correct (-07:00 with DST).
The timezone returned from the function is Chile/EasterIsland which I have a feeling is the cause. If I could, I would make this only work for the USA, but I do need it to be worldwide.
This is the function I have now. Please excuse the extremely messy code. I have been playing around with tons of things over the last few hours trying to figure out a solution.
Most of the functionality was found online.
function offsetToTZ($offset) {
switch((string) $offset) {
case '-04:30' : return 'America/Caracas'; break;
case '-03:30' : return 'Canada/Newfoundland'; break;
case '+03:30' : return 'Asia/Tehran'; break;
case '+04:30' : return 'Asia/Kabul'; break;
case '+05:30' : return 'Asia/Kolkata'; break;
case '+05:45' : return 'Asia/Kathmandu'; break;
case '+09:30' : return 'Australia/Darwin'; break;
}
$offset = (int) str_replace(array('0',0,':00',00,'30',30,'45',45,':','+'),'', (string) $offset);
$offset = $offset*60*60;
$abbrarray = timezone_abbreviations_list();
foreach ($abbrarray as $abbr) {
foreach($abbr as $city) {
if($city['offset'] == $offset) {
return $city['timezone_id'];
}
}
}
return false;
}
I included the switch/case for certain timezones that are :30 and :45 out there. There may be a way to include that also without the need of the switch/case.
NOTE: The offsets are always returned as such +00:00 or -00:00 from the geo IP API.
I would appreciate any help or a point in the right direction. I'm not very novice with PHP, but offsets are a new story for me. Thanks!
It can be done quite simply, by turning the offset into seconds and passing it to timezone_name_from_abbr:
<?php
$offset = '-7:00';
// Calculate seconds from offset
list($hours, $minutes) = explode(':', $offset);
$seconds = $hours * 60 * 60 + $minutes * 60;
// Get timezone name from seconds
$tz = timezone_name_from_abbr('', $seconds, 1);
// Workaround for bug #44780
if($tz === false) $tz = timezone_name_from_abbr('', $seconds, 0);
// Set timezone
date_default_timezone_set($tz);
echo $tz . ': ' . date('r');
The third parameter of timezone_name_from_abbr controls whether to adjust for daylight saving time or not.
timezone_name_from_abbr() will return false on some time zone offsets. In particular - Hawaii, which has a -10 from GMT offset, -36000 seconds.
References:
date_default_timezone_set('UTC');
$timezones = array();
foreach (DateTimeZone::listAbbreviations() as $key => $array)
{
$timezones = array_merge($timezones, $array);
}
$utc = new DateTimeZone('UTC');
$timezone_offset = '+02:00'; # 2H
$sign = substr($timezone_offset, 0, 1) == '+'? '': '-';
$offset = substr($timezone_offset, 1, 2) . 'H' . substr($timezone_offset, 4, 2) . 'M';
$operation = $sign == ''? 'add': 'sub';
$start = new DateTime('', $utc);
$date = new DateTime('', $utc);
$date->{$operation}(new DateInterval("PT{$offset}"));
$offset = $start->diff($date)->format('%r') . ($start->diff($date)->h * 3600 + $start->diff($date)->m * 60 + $start->diff($date)->s); # 7200 (2H)
echo $offset, PHP_EOL;
echo $date->format('Y-m-d H:i:s'), PHP_EOL;
foreach($timezones as $timezone)
{
if($timezone['offset'] == $offset)
{
echo $timezone['timezone_id'], PHP_EOL;
}
}
I might have misunderstood you in some parts, but I hope it helps, if you could be more specific, I might be more helpful.
For Chile I get:
-25200 (-7h)
2012-08-07 18:05:24 (current time 2012-08-08 01:05:24)
Chile/EasterIsland
Output of the example above:
7200
2012-08-08 02:49:56
Europe/London
Europe/Belfast
Europe/Gibraltar
Europe/Guernsey
Europe/Isle_of_Man
Europe/Jersey
GB
Africa/Khartoum
Africa/Blantyre
Africa/Bujumbura
Africa/Gaborone
Africa/Harare
Africa/Kigali
Africa/Lubumbashi
Africa/Lusaka
Africa/Maputo
Africa/Windhoek
Europe/Berlin
Africa/Algiers
Africa/Ceuta
Africa/Tripoli
Africa/Tunis
Arctic/Longyearbyen
Atlantic/Jan_Mayen
CET
Europe/Amsterdam
Europe/Andorra
Europe/Athens
Europe/Belgrade
Europe/Bratislava
Europe/Brussels
Europe/Budapest
Europe/Chisinau
Europe/Copenhagen
Europe/Gibraltar
Europe/Kaliningrad
Europe/Kiev
Europe/Lisbon
Europe/Ljubljana
Europe/Luxembourg
Europe/Madrid
Europe/Malta
Europe/Minsk
Europe/Monaco
Europe/Oslo
Europe/Paris
Europe/Podgorica
Europe/Prague
Europe/Riga
Europe/Rome
Europe/San_Marino
Europe/Sarajevo
Europe/Simferopol
Europe/Skopje
Europe/Sofia
Europe/Stockholm
Europe/Tallinn
Europe/Tirane
Europe/Tiraspol
Europe/Uzhgorod
Europe/Vaduz
Europe/Vatican
Europe/Vienna
Europe/Vilnius
Europe/Warsaw
Europe/Zagreb
Europe/Zaporozhye
Europe/Zurich
WET
Europe/Kaliningrad
Europe/Helsinki
Africa/Cairo
Africa/Tripoli
Asia/Amman
Asia/Beirut
Asia/Damascus
Asia/Gaza
Asia/Istanbul
Asia/Nicosia
EET
Europe/Athens
Europe/Bucharest
Europe/Chisinau
Europe/Istanbul
Europe/Kaliningrad
Europe/Kiev
Europe/Mariehamn
Europe/Minsk
Europe/Moscow
Europe/Nicosia
Europe/Riga
Europe/Simferopol
Europe/Sofia
Europe/Tallinn
Europe/Tiraspol
Europe/Uzhgorod
Europe/Vilnius
Europe/Warsaw
Europe/Zaporozhye
Asia/Jerusalem
Asia/Gaza
Asia/Tel_Aviv
MET
Africa/Johannesburg
Africa/Maseru
Africa/Mbabane
Africa/Windhoek
Africa/Windhoek
Africa/Ndjamena
Europe/Lisbon
Europe/Madrid
Europe/Monaco
Europe/Paris
WET
Europe/Luxembourg
Which nails my timezone.
$UTC_offset = '+03:00';
$date = new \DateTime('now', 'UTC');
var_dump($date);
$timezone = new \DateTimeZone(str_replace(':', '', $UTC_offset));
$date->setTimezone($timezone);
var_dump($date);
Results:
class DateTime#205 (3) {
public $date =>
string(26) "2015-01-20 06:00:00.000000"
public $timezone_type =>
int(3)
public $timezone =>
string(3) "UTC"
}
class DateTime#205 (3) {
public $date =>
string(26) "2015-01-20 09:00:00.000000"
public $timezone_type =>
int(1)
public $timezone =>
string(6) "+03:00"
}
You might want to have a look at DateTime PHP extension (it's enabled & included by default in all PHP versions >= 5.2.0, unless it was specifically disabled at compile time).
It does everything you need here quite well.
It is unadvised to map time zone offsets back to a time zone identifier. Many time zones share the same offset.
Even within a single country, this is problematic. Consider that in the United States, the -5 offset is used by both Central Standard Time (America/Chicago) and Eastern Daylight Time (America/New_York) at different times of the year.
Also consider that there are times where BOTH of those time zones use -5 at the same time. For example, Sunday November 3rd 2013 at 1:00 AM in UTC-5 could be either in CDT or EST. You'd have no way to distinguish just by -5 which time zone it was.
Nowadays the DateTimeZone constructor can explicitly accept a UTC offset, which I understand you have.
So just:
$timeZone = new DateTimeZone('+0100');
Documentation:
http://php.net/manual/en/datetimezone.construct.php
Note: per that documentation link, this new constructor usage has been available since PHP version 5.5.10.
You can use GMT time also and convert it to your requirement afterwards
<?php
echo gmdate("M d Y H:i:s", mktime(0, 0, 0, 1, 1, 1998));
?>
GMT refers Greenwich Mean Time which is common all over the world.
This work for me:
function Get_Offset_Date($Offset, $Unixtime = false, $Date_Format = 'Y.m.d,H:i')
{
try
{
$date = new DateTime("now",new DateTimeZone($Offset));
if($Unixtime)
{
$date->setTimestamp($Unixtime);
}
$Unixtime = $date->getTimestamp();
return $date->format($Date_Format);
}
catch(Exception $e)
{
return false;
}
}
To use it just call this to get current time:
echo Get_Offset_Date('+2:00');
And this for get Offset date (input is unixtime)
echo Get_Offset_Date('+2:00',1524783867);
来源：https://stackoverflow.com/questions/11820718/convert-utc-offset-to-timezone-or-date