Last updated: Fri, 16 Jul 2010

date_default_timezone_set

(PHP 5 >= 5.1.0)

date_default_timezone_set — Configura a timezone padrão a ser utilizada por todas as funções de data e hora em um script

Descrição

bool date_default_timezone_set ( string $timezone_identifier )

date_default_timezone_set() configura a timezone padrão a ser utilizada por todas as funções de data e hora em um script

Nota: Desde o PHP5.1.0 (quando as funções de data e tempo foram reescritas), toda chamada a esse tipo de função irá gerar um E_NOTICE se a timezone não é válida, e/ou uma mensagem E_STRICT se estiver utilizando as configurações do sistema ou a variável de ambiente TZ.

Ao invés de utilizar essa função para setar a timezone padrão no seu script, você pode também utilizar a configuração INI date.timezone para configurar a timezone padrão.

Parâmetros

timezone_identifier: O identificador da timezone, como UTC ou Europe/Lisbon. A lista de identificadores válidos está disponível em Lista de Timezones Suportados.

Valor Retornado

A função retorna FALSE se o timezone_identifier não é válido, ou TRUE caso contrário.

Exemplos

Exemplo #1 Lendo a timezone padrão


<?php
date_default_timezone_set('America/Los_Angeles');

$script_tz = date_default_timezone_get();

if (strcmp($script_tz, ini_get('date.timezone'))){
    echo 'Script timezone differs from ini-set timezone.';
} else {
    echo 'Script timezone and ini-set timezone match.';
}
?>

Histórico

Versão	Descrição
5.1.2	A função passou a validar o parâmetro `timezone_identifier`.

Veja Também

date_default_timezone_get() - Retorna a timezone padrão usada por todas as funções de data e tempo em um script

date_diff

date_default_timezone_get

Last updated: Fri, 16 Jul 2010

User Contributed Notes
date_default_timezone_set

Dane Iracleous
21-Jul-2010 05:48


Here is some useful code to set the default timezone to the user's local timezone. 



<?php

function getLocalTimezone()

{

    $iTime = time();

    $arr = localtime($iTime);

    $arr[5] += 1900; 

    $arr[4]++;

    $iTztime = gmmktime($arr[2], $arr[1], $arr[0], $arr[4], $arr[3], $arr[5], $arr[8]);

    $offset = doubleval(($iTztime-$iTime)/(60*60));

    $zonelist = 

    array

    (

        'Kwajalein' => -12.00,

        'Pacific/Midway' => -11.00,

        'Pacific/Honolulu' => -10.00,

        'America/Anchorage' => -9.00,

        'America/Los_Angeles' => -8.00,

        'America/Denver' => -7.00,

        'America/Tegucigalpa' => -6.00,

        'America/New_York' => -5.00,

        'America/Caracas' => -4.30,

        'America/Halifax' => -4.00,

        'America/St_Johns' => -3.30,

        'America/Argentina/Buenos_Aires' => -3.00,

        'America/Sao_Paulo' => -3.00,

        'Atlantic/South_Georgia' => -2.00,

        'Atlantic/Azores' => -1.00,

        'Europe/Dublin' => 0,

        'Europe/Belgrade' => 1.00,

        'Europe/Minsk' => 2.00,

        'Asia/Kuwait' => 3.00,

        'Asia/Tehran' => 3.30,

        'Asia/Muscat' => 4.00,

        'Asia/Yekaterinburg' => 5.00,

        'Asia/Kolkata' => 5.30,

        'Asia/Katmandu' => 5.45,

        'Asia/Dhaka' => 6.00,

        'Asia/Rangoon' => 6.30,

        'Asia/Krasnoyarsk' => 7.00,

        'Asia/Brunei' => 8.00,

        'Asia/Seoul' => 9.00,

        'Australia/Darwin' => 9.30,

        'Australia/Canberra' => 10.00,

        'Asia/Magadan' => 11.00,

        'Pacific/Fiji' => 12.00,

        'Pacific/Tongatapu' => 13.00

    );

    $index = array_keys($zonelist, $offset);

    if(sizeof($index)!=1)

        return false;

    return $index[0];

} 



date_default_timezone_set(getLocalTimezone());

?>

Frederick Hathaway
04-Mar-2010 01:54


It's really a hassle that there is no way to set the timezone offset. I attempted to use the code that searched for the correct timezone name by offset from below. I found it didn't work reliably since various cities may have different rules about time DST etc. My solution is to actually search the array and do a test to insure the offset is what I expect it to be. It seems very kludgey (if thats a word) but it works. 





<?php


function setTimezoneByOffset($offset) 


    {


      $testTimestamp = time();


        date_default_timezone_set('UTC');


        $testLocaltime = localtime($testTimestamp,true);


        $testHour = $testLocaltime['tm_hour'];        





      


    $abbrarray = timezone_abbreviations_list();


    foreach ($abbrarray as $abbr) 


    {


        //echo $abbr."<br>";


      foreach ($abbr as $city) 


      {


                date_default_timezone_set($city['timezone_id']);


                $testLocaltime     = localtime($testTimestamp,true);


                $hour                     = $testLocaltime['tm_hour'];        


                $testOffset =  $hour - $testHour;


                if($testOffset == $offset)


                {


                    return true;


                }


      }


    }


    return false;


    }


?>

Christopher Kramer
09-Jan-2010 01:52


I experienced that using this function highly increases performance of functions like getdate() or date() using PHP 5.2.6 on Windows.

I experienced similar results on Linux servers with PHP 5.2.6 and 5.2.10, although the difference was not that significant on these servers: The PHP 5.2.10 server did run with date_default_timezone_set ("only") twice as fast as without. The 5.2.6 server did 5 times faster with date_default_timezone_set. As you can see below, the 5.2.6-Windows machine did a LOT faster.

Of course these machines have completely different hardware and can not really be compared, but all show improved performance.



I checked PHP 4.4.9 on Windows (without date_default_timezone_set of course) and noticed that its as fast as PHP 5.2.6 with date_default_timezone_set.



The following script shows this:



<?php



# uncomment to see difference

# date_default_timezone_set(date_default_timezone_get());



function getmicrotime()

 {

 list($usec, $sec) = explode(' ',microtime());

 return ($sec.substr($usec,1,7));

 }

 

$start=mktime(0,0,0,1,1,2005);

$end=mktime(0,0,0,1,1,2020);

$nr=50000;

 

$start_time=getmicrotime();

for($i=0;$i<$nr;$i++) {

# $value=getdate(rand($start,$end));

  date("H:i:s d.m.Y",rand($start,$end));

}

$end_time=getmicrotime();



echo "Time: ".($end_time-$start_time);



// With date_default_timezone_set(): "Time: 0.379343986511"

// Without date_default_timezone_set(): "Time: 7.4971370697"



?>



Note that the timezone is not changed, it is only set again. I really wonder why this makes such a big performance difference, but its good to know.

ted dot chou12 at gmail dot com
03-Dec-2008 05:13


Timezone using other approaches:

<?php $datetime = strtotime($originaldatetime) + $time;

$datetime = date('M d, Y h:i A', $datetime);?>



$time obtained from table below:

-25200|International Date Line (West) GMT-12|

-21600|Midway Island, Samoa GMT-11|

-18000|Hawaii, Honolulu GMT-10|

-14400|Alaska GMT-9|

-10800|Pacific Standard Time, US, Canada GMT-8|

-7200|British Columbia N.E., Santa Fe, Mountain Time GMT-7|

-3600|Central America, Chicago, Guatamala, Mexico City GMT-6|

0|US, Canada, Bogota, Boston, New York GMT-5|

+3600|Canada, Santiago, Atlantic Standard Time GMT-4|

+7200|Brazilia, Buenos Aires, Georgetown, Greenland GMT-3|

+10800|Mid-Atlantic GMT-2|

+14400|Azores, Cape Verde Is., Western Africa Time GMT-1|

+18000|London, Iceland, Ireland, Morocco, Portugal GMT|

+21600|Amsterdam, Berlin, Bern, Madrid, Paris, Rome, GMT+1|

+25200|Athens, Cairo, Cape Town, Finland, Greece, Israel GMT+2|

+28800|Ankara, Aden, Baghdad, Beruit, Kuwait, Moscow GMT+3|

+32400|Abu Dhabi, Baku, Kabul, Tehran, Tbilisi, Volgograd GMT+4|

+36000|Calcutta, Colombo, Islamabad, Madras, New Dehli GMT+5|

+39600|Almaty, Dhakar, Kathmandu, Colombo, Sri Lanka GMT+6|

+43200|Bangkok, Hanoi, Jakarta, Phnom Penh, Australia GMT+7|

+46800|Taipei, Beijing, Hong Kong, Singapore, GMT+8|

+50400|Seoul, Tokyo, Central Australia GMT+9|

+54000|Brisbane, Canberra, Guam, Melbourne, Sydney, GMT+10|

+57600|Magadan, New Caledonia, Solomon Is. GMT+11|

+61200|Auckland, Fiji, Kamchatka, Marshall, Wellington, GMT+12|

jason at jasonpriem dot com
12-Nov-2008 02:29


While it's easy to change timezones based on names or abbreviations, I haven't found any straightforward way of doing so using an offset integer.  This situation comes up if you're using AJAX to get information about a user's timezone; javascript's getTimezoneOffset() method just sends you an offset number. So, here's my clunky solution: an adaptation of chris' function at http://us.php.net/manual/en/function.timezone-name-from-abbr.php.





<?php


    function set_tz_by_offset($offset) {


        $offset = $offset*60*60;


        $abbrarray = timezone_abbreviations_list();


        foreach ($abbrarray as $abbr) {


            //echo $abbr."<br>";


                foreach ($abbr as $city) {


                    //echo $city['offset']." $offset<br>";


                        if ($city['offset'] == $offset) { // remember to multiply $offset by -1 if you're getting it from js


                               date_default_timezone_set($city['timezone_id']);


                               return true;


                        }


                }


        }


    date_default_timezone_set("ust");


       return false;


       }





set_tz_by_offset(-1);





?>





[EDIT BY thiago AT php DOT net: This code has contributions from iateadonut at gmail dot com]

Anonymous
28-Sep-2008 02:34


If you have problems with errors, why the default is not set use this on the top of the script:



<?php

if(function_exists("date_default_timezone_set") and function_exists("date_default_timezone_get"))

@date_default_timezone_set(@date_default_timezone_get());

?>

Rob Kaper
15-Jul-2008 05:46


If you want users to choose their own timezones, here's some code that gets all available timezones but only uses one city for each possible value:



<?php



$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'] ) )

            $cities[$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 );



?>

PeerGoal.com
12-Feb-2007 10:21


The problem:



date() [function.date]: It is not safe to rely on the system's timezone settings. Please use the date.timezone setting, the TZ environment variable or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'America/Los_Angeles' for 'PST/-8.0/no DST' instead



Of course this is a problem that recently surfaced since PHP5. Quick fix is to set your time zone, add this line to your php code:



date_default_timezone_set("America/Los_Angeles");

davidn at datalinktech dot com dot au
21-Dec-2006 11:27


Note that there may be some unexpected side-effects that result from using either set_default_timezone() or the putenv("TZ=...") workalike for earlier PHP versions.  ANY date formatted and output either by PHP or its apache host process will be unconditionally expressed in that timezone.





[red. That is only true for the putenv() hack - Derick]





This does indeed include the web server's logs and other output files and reports which by default usually do not include any indication of timezone. This has a further side-effect on log processing and analysis, obviously.

date_diff

date_default_timezone_get

Last updated: Fri, 16 Jul 2010