timezone_name_from_abbr()

(PHP 5 >= 5.1.3, PHP 7)

Returns the timezone name from abbreviation

说明

timezone_name_from_abbr(string $abbr[,int $gmtOffset=-1[,int $isdst=-1]]): string

参数

$abbr

Time zone abbreviation.

$gmtOffset

Offset from GMT in seconds. Defaults to -1 which means that first found time zone corresponding to$abbris returned. Otherwise exact offset is searched and only if not found then the first time zone with any offset is returned.

$isdst

Daylight saving time indicator. Defaults to -1, which means that whether the time zone has daylight saving or not is not taken into consideration when searching. If this is set to 1, then the$gmtOffsetis assumed to be an offset with daylight saving in effect; if 0,then$gmtOffsetis assumed to be an offset without daylight saving in effect.If$abbrdoesn't exist then the time zone is searched solely by the$gmtOffsetand$isdst.

返回值

Returns time zone name on success 或者在失败时返回FALSE.

范例

Atimezone_name_from_abbr()example

<?php
echo timezone_name_from_abbr("CET") . "\n";
echo timezone_name_from_abbr("", 3600, 0) . "\n";
?>

以上例程的输出类似于：

Europe/Berlin
Europe/Paris

参见

• timezone_abbreviations_list() 别名 DateTimeZone::listAbbreviations

timezone_name_from_abbr() sometimes returns FALSE instead of an actual timezone: http://bugs.php.net/44780
It's possible to workaround it for some cases by getting the timezone name from timezone_abbreviations_list(). For example, if you have the GMT offset and want a timezone name:
<?php
/* Takes a GMT offset (in hours) and returns a timezone name */
function tz_offset_to_name($offset)
{
    $offset *= 3600; // convert hour offset to seconds
    $abbrarray = timezone_abbreviations_list();
    foreach ($abbrarray as $abbr)
    {
        foreach ($abbr as $city)
        {
            if ($city['offset'] == $offset)
            {
                return $city['timezone_id'];
            }
        }
    }
    return FALSE;
}
?>

In some cases, timezone_name_from_abbr() may return a "historical" (i.e. deprecated) timezone identifier rather than the current standard one for a given location. For example:
<?php
echo timezone_name_from_abbr('EASST'); // prints "Chile/EasterIsland" instead of "Pacific/Easter"
?>
This means that the returned timezone identifier is not guaranteed to be in the results of timezone_identifiers_list() unless you include the "backwards compatible" timezones.
<?php
var_dump(in_array(timezone_name_from_abbr('EASST'), timezone_identifiers_list())); // (bool)false
var_dump(in_array(timezone_name_from_abbr('EASST'), timezone_identifiers_list(DateTimeZone::ALL_WITH_BC))); // (bool)true
?>

Another way to do this is to wrap the function in a class that extends the DateTimeZone class:
<?php
/**
 * Helps with timezones.
 * @link http://us.php.net/manual/en/class.datetimezone.php
 *
 * @package Date
 */
class Helper_DateTimeZone extends DateTimeZone
{
  /**
   * Converts a timezone hourly offset to its timezone's name.
   * @example $offset = -5, $isDst = 0 <=> return value = 'America/New_York'
   * 
   * @param float $offset The timezone's offset in hours.
   *           Lowest value: -12 (Pacific/Kwajalein)
   *           Highest value: 14 (Pacific/Kiritimati)
   * @param bool $isDst Is the offset for the timezone when it's in daylight
   *           savings time?
   * 
   * @return string The name of the timezone: 'Asia/Tokyo', 'Europe/Paris', ...
   */
  final public static function tzOffsetToName($offset, $isDst = null)
  {
    if ($isDst === null)
    {
      $isDst = date('I');
    }
    $offset *= 3600;
    $zone  = timezone_name_from_abbr('', $offset, $isDst);
    if ($zone === false)
    {
      foreach (timezone_abbreviations_list() as $abbr)
      {
        foreach ($abbr as $city)
        {
          if ((bool)$city['dst'] === (bool)$isDst &&
            strlen($city['timezone_id']) > 0  &&
            $city['offset'] == $offset)
          {
            $zone = $city['timezone_id'];
            break;
          }
        }
        if ($zone !== false)
        {
          break;
        }
      }
    }
  
    return $zone;
  }
}
?>
Then you could do something like this:
<?php
$Dtz = new Helper_DateTimeZone(Helper_DateTimeZone::tzOffsetToName(-5));
var_dump($Dtz->getName());
string(16) "America/New_York"
?>

Fun fact: (60*60) * -2 always seems to return null.
Perhaps because there's no timezone that corresponds to UTC -2.