php DateTimeZone->getOffset() 返回 GMT 时区的无效偏移量

Question

希望有人注意到我遇到的问题的原因。

对于所有其他时区，例如“欧洲/赫尔辛基”，下面的偏移量计算返回正确的值，但出于某种原因，我得到“Etc/GMT+2”样式时区的负值，反之亦然(例如，对于 Etc/GMT- 2 我得到正值，7200)。

$dateTimeZone = new DateTimeZone('Etc/GMT+2');
echo $dateTimeZone->getOffset(new DateTime("now", new DateTimezone( 'UTC' )));

预期:7200结果:-7200

Answer 1

Etc/GMT+2时区否则将被称为“GMT -2”或表示为 <date time>-02:00 .

这是由于 POSIX 表示这些类型的时区偏移的方式:

The offset specifies the time value you must add to the local time to get a Coordinated Universal Time value. It has syntax like [+|-]hh[:mm[:ss]]. This is positive if the local time zone is west of the Prime Meridian and negative if it is east. The hour must be between 0 and 23, and the minute and seconds between 0 and 59.

^{From TZ Variable.}

和:

Numeric time zone abbreviations typically count hours east of UTC, e.g., +09 for Japan and -10 for Hawaii. However, the POSIX TZ environment variable uses the opposite convention. For example, one might use TZ="JST-9" and TZ="HST10" for Japan and Hawaii, respectively. If the tz database is available, it is usually better to use settings like TZ="Asia/Tokyo" and TZ="Pacific/Honolulu" instead, as this should avoid confusion, handle old time stamps better, and insulate you better from any future changes to the rules. One should never set POSIX TZ to a value like "GMT-9", though, since this would falsely claim that local time is nine hours ahead of UTC and the time zone is called "GMT".

^{From Sources for Time Zone and Daylight Saving Time Data - Time notation.}