时区数据库文件格式问题答案

【问题标题】：Timezone database file format question时区数据库文件格式问题
【发布时间】：2011-06-11 17:19:53
【问题描述】：

我正在读取从Olson 数据库生成的时区文件，以查找时区何时更改以及它们更改为什么。 tzfile.h 中描述了时区文件的格式。

对于我的问题，我将使用我获得的欧洲/罗马数据。

我可能让它正常工作，因为我的输出正确匹配 timeanddate.com 所说的内容。例如，我的程序正确地说：

1982 年 3 月 28 日 02:00:00 时区更改为 GMT +2.000000。

1982 年 9 月 26 日 03:00:00 时区更改为 GMT +1.000000。

这在此处得到确认： http://www.timeanddate.com/worldclock/clockchange.html?n=215&year=1982

但是，我不确定是否需要使用 tzh_ttisstdcnt 和 tzh_ttisgmtcnt。

来自 tzfile.h：

然后有 tzh_ttisstdcnt 标准/墙壁指示器，每个存储作为一个字节的值；他们告诉是否相关的过渡时间指定了本地时间类型作为标准时间或挂钟时间，并且在时区文件为用于处理 POSIX 风格的时区环境变量。

最后还有 tzh_ttisgmtcnt UTC/本地指标，每个都存储为一字节值；他们告诉是否相关的过渡时间与本地时间类型是指定为 UTC 或本地时间，以及使用时区文件时使用在处理 POSIX 风格的时区环境变量。

我发现每个“时间类型”（ttinfo 结构）都有一个 isstd 和 isgmt 字节。以下是欧洲/罗马的 6 种“时间类型”：

 Type 0, CEST, DST? = 1, GMT+2, isstd? = 1, isgmt? = 0
 Type 1, CET,  DST? = 0, GMT+1, isstd? = 1, isgmt? = 0
 Type 2, CEST, DST? = 1, GMT+2, isstd? = 0, isgmt? = 0
 Type 3, CET,  DST? = 0, GMT+1, isstd? = 0, isgmt? = 0
 Type 4, CEST, DST? = 1, GMT+2, isstd? = 1, isgmt? = 1
 Type 5, CET,  DST? = 0, GMT+1, isstd? = 1, isgmt? = 1

tzfile.h 听起来像是 isstd 和 isgmt 告诉您转换时间是如何存储的（gmt vs localtime）。但是，我的代码当前假定所有转换时间都存储为 GMT。对于所有 6 种转换类型，我的程序的输出都与 timeanddate.com 匹配。

另外，我不明白类型 0 和 1 如何可以是 std 而不是 gmt。我以为 GMT 是标准时间。

任何解释都会很棒。

编辑：

当我忽略 isstd 和 isgmt 选项时，我的输出似乎与 timeanddate.com 上的数据几乎匹配。我目前将所有转换时间解释为 GMT：

罗马的过渡类型：

新类型 0： isdst = 1 偏移量 = 7200 缩写 = 0 isstd = 1 isgmt = 0

新类型 1： isdst = 0 偏移量 = 3600 缩写 = 5 isstd = 1 isgmt = 0

新类型 2： isdst = 1 偏移量 = 7200 缩写 = 0 isstd = 0 isgmt = 0

新类型 3： isdst = 0 偏移量 = 3600 缩写 = 5 isstd = 0 isgmt = 0

新类型 4： isdst = 1 偏移量 = 7200 缩写 = 0 isstd = 1 isgmt = 1

罗马的数据（假设所有过渡时间均以 GMT 时间给出）：

The starting timezone is GMT+1
type: 0, transition time in file:-1690851600
Add previous offset to get transition as (localtime): June 03, 1916 00:00:00 GMT+2

**type: 1, transition time in file:-1680483600
Add previous offset to get transition as (localtime): October 01, 1916 01:00:00 GMT+1**

type: 0, transition time in file:-1664758800
Add previous offset to get transition as (localtime): April 01, 1917 00:00:00 GMT+2

type: 1, transition time in file:-1649034000
Add previous offset to get transition as (localtime): September 30, 1917 01:00:00 GMT+1

type: 0, transition time in file:-1635123600
Add previous offset to get transition as (localtime): March 10, 1918 00:00:00 GMT+2

type: 1, transition time in file:-1616979600
Add previous offset to get transition as (localtime): October 06, 1918 01:00:00 GMT+1

type: 0, transition time in file:-1604278800
Add previous offset to get transition as (localtime): March 02, 1919 00:00:00 GMT+2

type: 1, transition time in file:-1585530000
Add previous offset to get transition as (localtime): October 05, 1919 01:00:00 GMT+1

type: 0, transition time in file:-1571014800
Add previous offset to get transition as (localtime): March 21, 1920 00:00:00 GMT+2

type: 1, transition time in file:-1555290000
Add previous offset to get transition as (localtime): September 19, 1920 01:00:00 GMT+1

type: 0, transition time in file:-932432400
Add previous offset to get transition as (localtime): June 15, 1940 00:00:00 GMT+2

type: 1, transition time in file:-857257200
Add previous offset to get transition as (localtime): November 02, 1942 03:00:00 GMT+1

type: 0, transition time in file:-844556400
Add previous offset to get transition as (localtime): March 29, 1943 02:00:00 GMT+2

type: 1, transition time in file:-828226800
Add previous offset to get transition as (localtime): October 04, 1943 03:00:00 GMT+1

type: 0, transition time in file:-812502000
Add previous offset to get transition as (localtime): April 03, 1944 02:00:00 GMT+2

type: 1, transition time in file:-798080400
Add previous offset to get transition as (localtime): September 17, 1944 01:00:00 GMT+1

type: 2, transition time in file:-781052400
Add previous offset to get transition as (localtime): April 02, 1945 02:00:00 GMT+2

type: 1, transition time in file:-766717200
Add previous offset to get transition as (localtime): September 15, 1945 01:00:00 GMT+1

type: 0, transition time in file:-750898800
Add previous offset to get transition as (localtime): March 17, 1946 02:00:00 GMT+2

type: 1, transition time in file:-733359600
Add previous offset to get transition as (localtime): October 06, 1946 03:00:00 GMT+1

type: 0, transition time in file:-719456400
Add previous offset to get transition as (localtime): March 16, 1947 00:00:00 GMT+2

type: 1, transition time in file:-701917200
Add previous offset to get transition as (localtime): October 05, 1947 01:00:00 GMT+1

type: 0, transition time in file:-689209200
Add previous offset to get transition as (localtime): February 29, 1948 02:00:00 GMT+2

type: 1, transition time in file:-670460400
Add previous offset to get transition as (localtime): October 03, 1948 03:00:00 GMT+1

type: 2, transition time in file:-114051600
Add previous offset to get transition as (localtime): May 22, 1966 00:00:00 GMT+2

type: 3, transition time in file:-103168800
Add previous offset to get transition as (localtime): September 25, 1966 00:00:00 GMT+1

type: 2, transition time in file:-81997200
Add previous offset to get transition as (localtime): May 28, 1967 00:00:00 GMT+2

type: 3, transition time in file:-71719200
Add previous offset to get transition as (localtime): September 24, 1967 00:00:00 GMT+1

type: 2, transition time in file:-50547600
Add previous offset to get transition as (localtime): May 26, 1968 00:00:00 GMT+2

type: 3, transition time in file:-40269600
Add previous offset to get transition as (localtime): September 22, 1968 00:00:00 GMT+1

type: 2, transition time in file:-18493200
Add previous offset to get transition as (localtime): June 01, 1969 00:00:00 GMT+2

type: 3, transition time in file:-8215200
Add previous offset to get transition as (localtime): September 28, 1969 00:00:00 GMT+1

type: 2, transition time in file:12956400
Add previous offset to get transition as (localtime): May 31, 1970 00:00:00 GMT+2

type: 3, transition time in file:23234400
Add previous offset to get transition as (localtime): September 27, 1970 00:00:00 GMT+1

type: 2, transition time in file:43801200
Add previous offset to get transition as (localtime): May 23, 1971 00:00:00 GMT+2

type: 3, transition time in file:54687600
Add previous offset to get transition as (localtime): September 26, 1971 01:00:00 GMT+1

type: 2, transition time in file:75855600
Add previous offset to get transition as (localtime): May 28, 1972 00:00:00 GMT+2

type: 3, transition time in file:86738400
Add previous offset to get transition as (localtime): October 01, 1972 00:00:00 GMT+1

type: 2, transition time in file:107910000
Add previous offset to get transition as (localtime): June 03, 1973 00:00:00 GMT+2

type: 3, transition time in file:118188000
Add previous offset to get transition as (localtime): September 30, 1973 00:00:00 GMT+1

type: 2, transition time in file:138754800
Add previous offset to get transition as (localtime): May 26, 1974 00:00:00 GMT+2

type: 3, transition time in file:149637600
Add previous offset to get transition as (localtime): September 29, 1974 00:00:00 GMT+1

type: 0, transition time in file:170809200
Add previous offset to get transition as (localtime): June 01, 1975 00:00:00 GMT+2

type: 1, transition time in file:181090800
Add previous offset to get transition as (localtime): September 28, 1975 01:00:00 GMT+1

type: 0, transition time in file:202258800
Add previous offset to get transition as (localtime): May 30, 1976 00:00:00 GMT+2

type: 1, transition time in file:212540400
Add previous offset to get transition as (localtime): September 26, 1976 01:00:00 GMT+1

type: 0, transition time in file:233103600
Add previous offset to get transition as (localtime): May 22, 1977 00:00:00 GMT+2

type: 1, transition time in file:243990000
Add previous offset to get transition as (localtime): September 25, 1977 01:00:00 GMT+1

type: 0, transition time in file:265158000
Add previous offset to get transition as (localtime): May 28, 1978 00:00:00 GMT+2

type: 1, transition time in file:276044400
Add previous offset to get transition as (localtime): October 01, 1978 01:00:00 GMT+1

type: 0, transition time in file:296607600
Add previous offset to get transition as (localtime): May 27, 1979 00:00:00 GMT+2

type: 1, transition time in file:307494000
Add previous offset to get transition as (localtime): September 30, 1979 01:00:00 GMT+1

type: 4, transition time in file:323830800
Add previous offset to get transition as (localtime): April 06, 1980 02:00:00 GMT+2

type: 5, transition time in file:338950800
Add previous offset to get transition as (localtime): September 28, 1980 03:00:00 GMT+1

type: 4, transition time in file:354675600
Add previous offset to get transition as (localtime): March 29, 1981 02:00:00 GMT+2

type: 5, transition time in file:370400400
Add previous offset to get transition as (localtime): September 27, 1981 03:00:00 GMT+1

type: 4, transition time in file:386125200
Add previous offset to get transition as (localtime): March 28, 1982 02:00:00 GMT+2

type: 5, transition time in file:401850000
Add previous offset to get transition as (localtime): September 26, 1982 03:00:00 GMT+1

type: 4, transition time in file:417574800
Add previous offset to get transition as (localtime): March 27, 1983 02:00:00 GMT+2

type: 5, transition time in file:433299600
Add previous offset to get transition as (localtime): September 25, 1983 03:00:00 GMT+1

type: 4, transition time in file:449024400
Add previous offset to get transition as (localtime): March 25, 1984 02:00:00 GMT+2

type: 5, transition time in file:465354000
Add previous offset to get transition as (localtime): September 30, 1984 03:00:00 GMT+1

type: 4, transition time in file:481078800
Add previous offset to get transition as (localtime): March 31, 1985 02:00:00 GMT+2

type: 5, transition time in file:496803600
Add previous offset to get transition as (localtime): September 29, 1985 03:00:00 GMT+1

type: 4, transition time in file:512528400
Add previous offset to get transition as (localtime): March 30, 1986 02:00:00 GMT+2

type: 5, transition time in file:528253200
Add previous offset to get transition as (localtime): September 28, 1986 03:00:00 GMT+1

type: 4, transition time in file:543978000
Add previous offset to get transition as (localtime): March 29, 1987 02:00:00 GMT+2

type: 5, transition time in file:559702800
Add previous offset to get transition as (localtime): September 27, 1987 03:00:00 GMT+1

type: 4, transition time in file:575427600
Add previous offset to get transition as (localtime): March 27, 1988 02:00:00 GMT+2

type: 5, transition time in file:591152400
Add previous offset to get transition as (localtime): September 25, 1988 03:00:00 GMT+1

type: 4, transition time in file:606877200
Add previous offset to get transition as (localtime): March 26, 1989 02:00:00 GMT+2

type: 5, transition time in file:622602000
Add previous offset to get transition as (localtime): September 24, 1989 03:00:00 GMT+1

type: 4, transition time in file:638326800
Add previous offset to get transition as (localtime): March 25, 1990 02:00:00 GMT+2

type: 5, transition time in file:654656400
Add previous offset to get transition as (localtime): September 30, 1990 03:00:00 GMT+1

type: 4, transition time in file:670381200
Add previous offset to get transition as (localtime): March 31, 1991 02:00:00 GMT+2

type: 5, transition time in file:686106000
Add previous offset to get transition as (localtime): September 29, 1991 03:00:00 GMT+1

type: 4, transition time in file:701830800
Add previous offset to get transition as (localtime): March 29, 1992 02:00:00 GMT+2

type: 5, transition time in file:717555600
Add previous offset to get transition as (localtime): September 27, 1992 03:00:00 GMT+1

type: 4, transition time in file:733280400
Add previous offset to get transition as (localtime): March 28, 1993 02:00:00 GMT+2

type: 5, transition time in file:749005200
Add previous offset to get transition as (localtime): September 26, 1993 03:00:00 GMT+1

type: 4, transition time in file:764730000
Add previous offset to get transition as (localtime): March 27, 1994 02:00:00 GMT+2

type: 5, transition time in file:780454800
Add previous offset to get transition as (localtime): September 25, 1994 03:00:00 GMT+1

type: 4, transition time in file:796179600
Add previous offset to get transition as (localtime): March 26, 1995 02:00:00 GMT+2

type: 5, transition time in file:811904400
Add previous offset to get transition as (localtime): September 24, 1995 03:00:00 GMT+1

type: 4, transition time in file:828234000
Add previous offset to get transition as (localtime): March 31, 1996 02:00:00 GMT+2

type: 5, transition time in file:846378000
Add previous offset to get transition as (localtime): October 27, 1996 03:00:00 GMT+1

type: 4, transition time in file:859683600
Add previous offset to get transition as (localtime): March 30, 1997 02:00:00 GMT+2

type: 5, transition time in file:877827600
Add previous offset to get transition as (localtime): October 26, 1997 03:00:00 GMT+1

type: 4, transition time in file:891133200
Add previous offset to get transition as (localtime): March 29, 1998 02:00:00 GMT+2

type: 5, transition time in file:909277200
Add previous offset to get transition as (localtime): October 25, 1998 03:00:00 GMT+1

type: 4, transition time in file:922582800
Add previous offset to get transition as (localtime): March 28, 1999 02:00:00 GMT+2

type: 5, transition time in file:941331600
Add previous offset to get transition as (localtime): October 31, 1999 03:00:00 GMT+1

type: 4, transition time in file:954032400
Add previous offset to get transition as (localtime): March 26, 2000 02:00:00 GMT+2

type: 5, transition time in file:972781200
Add previous offset to get transition as (localtime): October 29, 2000 03:00:00 GMT+1

type: 4, transition time in file:985482000
Add previous offset to get transition as (localtime): March 25, 2001 02:00:00 GMT+2

type: 5, transition time in file:1004230800
Add previous offset to get transition as (localtime): October 28, 2001 03:00:00 GMT+1

type: 4, transition time in file:1017536400
Add previous offset to get transition as (localtime): March 31, 2002 02:00:00 GMT+2

type: 5, transition time in file:1035680400
Add previous offset to get transition as (localtime): October 27, 2002 03:00:00 GMT+1

type: 4, transition time in file:1048986000
Add previous offset to get transition as (localtime): March 30, 2003 02:00:00 GMT+2

type: 5, transition time in file:1067130000
Add previous offset to get transition as (localtime): October 26, 2003 03:00:00 GMT+1

type: 4, transition time in file:1080435600
Add previous offset to get transition as (localtime): March 28, 2004 02:00:00 GMT+2

type: 5, transition time in file:1099184400
Add previous offset to get transition as (localtime): October 31, 2004 03:00:00 GMT+1

type: 4, transition time in file:1111885200
Add previous offset to get transition as (localtime): March 27, 2005 02:00:00 GMT+2

type: 5, transition time in file:1130634000
Add previous offset to get transition as (localtime): October 30, 2005 03:00:00 GMT+1

type: 4, transition time in file:1143334800
Add previous offset to get transition as (localtime): March 26, 2006 02:00:00 GMT+2

type: 5, transition time in file:1162083600
Add previous offset to get transition as (localtime): October 29, 2006 03:00:00 GMT+1

type: 4, transition time in file:1174784400
Add previous offset to get transition as (localtime): March 25, 2007 02:00:00 GMT+2

type: 5, transition time in file:1193533200
Add previous offset to get transition as (localtime): October 28, 2007 03:00:00 GMT+1

type: 4, transition time in file:1206838800
Add previous offset to get transition as (localtime): March 30, 2008 02:00:00 GMT+2

type: 5, transition time in file:1224982800
Add previous offset to get transition as (localtime): October 26, 2008 03:00:00 GMT+1

type: 4, transition time in file:1238288400
Add previous offset to get transition as (localtime): March 29, 2009 02:00:00 GMT+2

type: 5, transition time in file:1256432400
Add previous offset to get transition as (localtime): October 25, 2009 03:00:00 GMT+1

type: 4, transition time in file:1269738000
Add previous offset to get transition as (localtime): March 28, 2010 02:00:00 GMT+2

type: 5, transition time in file:1288486800
Add previous offset to get transition as (localtime): October 31, 2010 03:00:00 GMT+1

type: 4, transition time in file:1301187600
Add previous offset to get transition as (localtime): March 27, 2011 02:00:00 GMT+2

type: 5, transition time in file:1319936400
Add previous offset to get transition as (localtime): October 30, 2011 03:00:00 GMT+1

type: 4, transition time in file:1332637200
Add previous offset to get transition as (localtime): March 25, 2012 02:00:00 GMT+2

type: 5, transition time in file:1351386000
Add previous offset to get transition as (localtime): October 28, 2012 03:00:00 GMT+1

type: 4, transition time in file:1364691600
Add previous offset to get transition as (localtime): March 31, 2013 02:00:00 GMT+2

type: 5, transition time in file:1382835600
Add previous offset to get transition as (localtime): October 27, 2013 03:00:00 GMT+1

type: 4, transition time in file:1396141200
Add previous offset to get transition as (localtime): March 30, 2014 02:00:00 GMT+2

type: 5, transition time in file:1414285200
Add previous offset to get transition as (localtime): October 26, 2014 03:00:00 GMT+1

type: 4, transition time in file:1427590800
Add previous offset to get transition as (localtime): March 29, 2015 02:00:00 GMT+2

type: 5, transition time in file:1445734800
Add previous offset to get transition as (localtime): October 25, 2015 03:00:00 GMT+1

type: 4, transition time in file:1459040400
Add previous offset to get transition as (localtime): March 27, 2016 02:00:00 GMT+2

type: 5, transition time in file:1477789200
Add previous offset to get transition as (localtime): October 30, 2016 03:00:00 GMT+1

type: 4, transition time in file:1490490000
Add previous offset to get transition as (localtime): March 26, 2017 02:00:00 GMT+2

type: 5, transition time in file:1509238800
Add previous offset to get transition as (localtime): October 29, 2017 03:00:00 GMT+1

type: 4, transition time in file:1521939600
Add previous offset to get transition as (localtime): March 25, 2018 02:00:00 GMT+2

type: 5, transition time in file:1540688400
Add previous offset to get transition as (localtime): October 28, 2018 03:00:00 GMT+1

type: 4, transition time in file:1553994000
Add previous offset to get transition as (localtime): March 31, 2019 02:00:00 GMT+2

type: 5, transition time in file:1572138000
Add previous offset to get transition as (localtime): October 27, 2019 03:00:00 GMT+1

type: 4, transition time in file:1585443600
Add previous offset to get transition as (localtime): March 29, 2020 02:00:00 GMT+2

type: 5, transition time in file:1603587600
Add previous offset to get transition as (localtime): October 25, 2020 03:00:00 GMT+1

type: 4, transition time in file:1616893200
Add previous offset to get transition as (localtime): March 28, 2021 02:00:00 GMT+2

type: 5, transition time in file:1635642000
Add previous offset to get transition as (localtime): October 31, 2021 03:00:00 GMT+1

type: 4, transition time in file:1648342800
Add previous offset to get transition as (localtime): March 27, 2022 02:00:00 GMT+2

type: 5, transition time in file:1667091600
Add previous offset to get transition as (localtime): October 30, 2022 03:00:00 GMT+1

type: 4, transition time in file:1679792400
Add previous offset to get transition as (localtime): March 26, 2023 02:00:00 GMT+2

type: 5, transition time in file:1698541200
Add previous offset to get transition as (localtime): October 29, 2023 03:00:00 GMT+1

type: 4, transition time in file:1711846800
Add previous offset to get transition as (localtime): March 31, 2024 02:00:00 GMT+2

type: 5, transition time in file:1729990800
Add previous offset to get transition as (localtime): October 27, 2024 03:00:00 GMT+1

type: 4, transition time in file:1743296400
Add previous offset to get transition as (localtime): March 30, 2025 02:00:00 GMT+2

type: 5, transition time in file:1761440400
Add previous offset to get transition as (localtime): October 26, 2025 03:00:00 GMT+1

type: 4, transition time in file:1774746000
Add previous offset to get transition as (localtime): March 29, 2026 02:00:00 GMT+2

type: 5, transition time in file:1792890000
Add previous offset to get transition as (localtime): October 25, 2026 03:00:00 GMT+1

type: 4, transition time in file:1806195600
Add previous offset to get transition as (localtime): March 28, 2027 02:00:00 GMT+2

type: 5, transition time in file:1824944400
Add previous offset to get transition as (localtime): October 31, 2027 03:00:00 GMT+1

type: 4, transition time in file:1837645200
Add previous offset to get transition as (localtime): March 26, 2028 02:00:00 GMT+2

type: 5, transition time in file:1856394000
Add previous offset to get transition as (localtime): October 29, 2028 03:00:00 GMT+1

type: 4, transition time in file:1869094800
Add previous offset to get transition as (localtime): March 25, 2029 02:00:00 GMT+2

type: 5, transition time in file:1887843600
Add previous offset to get transition as (localtime): October 28, 2029 03:00:00 GMT+1

type: 4, transition time in file:1901149200
Add previous offset to get transition as (localtime): March 31, 2030 02:00:00 GMT+2

type: 5, transition time in file:1919293200
Add previous offset to get transition as (localtime): October 27, 2030 03:00:00 GMT+1

type: 4, transition time in file:1932598800
Add previous offset to get transition as (localtime): March 30, 2031 02:00:00 GMT+2

type: 5, transition time in file:1950742800
Add previous offset to get transition as (localtime): October 26, 2031 03:00:00 GMT+1

type: 4, transition time in file:1964048400
Add previous offset to get transition as (localtime): March 28, 2032 02:00:00 GMT+2

type: 5, transition time in file:1982797200
Add previous offset to get transition as (localtime): October 31, 2032 03:00:00 GMT+1

type: 4, transition time in file:1995498000
Add previous offset to get transition as (localtime): March 27, 2033 02:00:00 GMT+2

type: 5, transition time in file:2014246800
Add previous offset to get transition as (localtime): October 30, 2033 03:00:00 GMT+1

type: 4, transition time in file:2026947600
Add previous offset to get transition as (localtime): March 26, 2034 02:00:00 GMT+2

type: 5, transition time in file:2045696400
Add previous offset to get transition as (localtime): October 29, 2034 03:00:00 GMT+1

type: 4, transition time in file:2058397200
Add previous offset to get transition as (localtime): March 25, 2035 02:00:00 GMT+2

type: 5, transition time in file:2077146000
Add previous offset to get transition as (localtime): October 28, 2035 03:00:00 GMT+1

type: 4, transition time in file:2090451600
Add previous offset to get transition as (localtime): March 30, 2036 02:00:00 GMT+2

type: 5, transition time in file:2108595600
Add previous offset to get transition as (localtime): October 26, 2036 03:00:00 GMT+1

type: 4, transition time in file:2121901200
Add previous offset to get transition as (localtime): March 29, 2037 02:00:00 GMT+2

type: 5, transition time in file:2140045200
Add previous offset to get transition as (localtime): October 25, 2037 03:00:00 GMT+1

我的第 2 次和第 4 次转换比here 列出的要晚一个小时，但几乎其他所有内容看起来都匹配。

【问题讨论】：

标签： unix timezone

【解决方案1】：

“标准时间”是指“冬令时”，而不是“夏令时”或“夏令时”。是的，GMT（松散地；严格地说，UTC）是“时间标准”，但它与您数据中的“isstd”列所指的内容并不完全相同。

'isstd' 为 0 或 1 的意义在于，欧洲的转换时间（通常）指定为在当前时区的 02:00 发生。

因此，欧洲/罗马的时钟走了：

1982-03-28 01:59:59 (UTC+01:00)
1982-03-28 03:00:00 (UTC+02:00)

据记录，此转换发生在标准时间 02:00（isstd = 1），但这不是 UTC (GMT) 时间；因此，它是您列表中的 0 型转换。相反，在秋天，时钟走了：

1982-09-26 01:59:59 (UTC+02:00)
1982-09-26 01:00:00 (UTC+01:00)

据记录，转换发生在转换前的时区 02:00，因此 isstd = 0（但它不是 UTC (GMT) 时间）；因此，这是您列表中的第 3 类转换。

其他组合（类型 1、2、4、5）出现在其他情况下。对于相同的两个转换，您将使用类型 4 条目并将更改时间记录为 01:00 UTC（因为 01:00:00+00:00 与 02:00:00+01:00 相同；并且您将使用类型 5 条目并将更改时间记录为 00:00 UTC（因为 00:00:00+00:00 与 02:00:00+02:00 相同）。请注意此处的切换时间彼此不同。描述中的类似差异适用于类型 1 和 2。

【讨论】：

感谢您解释它是如何工作的。如果我理解正确，文件中的转换时间并不总是存储为 GMT（不含 DST）。 isstd 和 isgmt 告诉你它们是如何存储的？我想将它们全部转换为 GMT。如果转换时间的类型为 isstd=1 且 isgmt=1，则 trans.时间已经存储为 GMT，对吗？如果 isstd=1 和 isgmt = 0，我会减去转换前本地时间的偏移量吗？如果 isstd=0 且 isgmt = 1，是否假定 DST 只有 1 小时？所以我会从过渡时间减去 1 小时将其转换为 GMT（没有 DST）？再次感谢！
我什至会说“转换时间通常不存储为 GMT”。考虑比欧洲/罗马更远离 UTC 的时区。例如，America/Los_Angeles 的切换时间为 02:00，但这是本地时间，而不是 UTC 时间。我相信，但是自从我上次查看代码以来已经有好几年了，isstd 和 isgmt 告诉你时间是如何存储的。您可以展开表格以显示存储的转换时间。我认为在没有相反指示的情况下，跳跃被假定为一个小时；只有历史区域有不同的价值，AFAIK。
“标准时间”指的是“冬季时间”……除非你在俄罗斯：timeanddate.com/news/time/russia-winter-time.html ;-)
@JonathanLeffler 解释很深入，但您说第一种类型是 0 型。实际上它是 4 型，如最初的帖子所示。这对您的答案有何影响？
@Jason：我必须尽快了解 Olson 数据库格式，自从我回答这个问题以来，它已经被调整过了。唯一快速的答案是“我不知道”。我需要一些时间。

【解决方案2】：

我打算编辑我的原始帖子，但它说它太长了：

更新：

我认为我的数据是正确的，TimeAndDate.com 有一个小错误。

在我的测试中，我专注于罗马的前 2 个过渡。

我的数据是：

类型：0，转换时间在文件：-1690851600

添加上一个偏移量获取本地过渡时间：6月03日， 1916 00:00:00 新时区为 GMT+2

类型：1，转换时间在文件：-1680483600

添加上一个偏移量获取本地过渡时间：10 月 01, 1916 01:00:00 新时区是格林威治标准时间+1

TimeAndDate的数据显示：

1.) 1916 年 6 月 3 日星期六晚上 11:59:59

1916 年 6 月 4 日星期日 12:00:00 午夜 → 凌晨 1:00:00 +1h UTC+2h CEST DST 开始

2.) 1916 年 9 月 30 日星期六 11:59:59 下午

12:00:00 午夜 → 11:00:00 PM 没有 UTC+1h CET DST 结束

我将计算机的时区和当地时间设置为与罗马匹配。然后，我运行了以下代码：

time_t rome_ts;
struct tm * rome_info;
char rome_buffer[75];

printf("My first transition:\n");

rome_ts = -1690851601;
rome_info = localtime(&rome_ts);
printf("Timestamp: %ld\n",rome_ts);
strftime(rome_buffer,75,"%A %B %d, %Y %H:%M:%S %Z",rome_info);
printf("%s, dst? = %d\n",rome_buffer,rome_info->tm_isdst);
printf("\n");

rome_ts = -1690851600;
rome_info = localtime(&rome_ts);
printf("Timestamp: %ld\n",rome_ts);
strftime(rome_buffer,75,"%A %B %d, %Y %H:%M:%S %Z",rome_info);
printf("%s, dst? = %d\n",rome_buffer,rome_info->tm_isdst);
printf("\n");

rome_ts = -1690851599;
rome_info = localtime(&rome_ts);
printf("Timestamp: %ld\n",rome_ts);
strftime(rome_buffer,75,"%A %B %d, %Y %H:%M:%S %Z",rome_info);
printf("%s, dst? = %d\n",rome_buffer,rome_info->tm_isdst);
printf("\n\n\n");


printf("TimeandDate.com's first transition:\n");

rome_ts = -1690768801;
rome_info = localtime(&rome_ts);
printf("Timestamp: %ld\n",rome_ts);
strftime(rome_buffer,75,"%A %B %d, %Y %H:%M:%S %Z",rome_info);
printf("%s, dst? = %d\n",rome_buffer,rome_info->tm_isdst);
printf("\n");

rome_ts = -1690768800;
rome_info = localtime(&rome_ts);
printf("Timestamp: %ld\n",rome_ts);
strftime(rome_buffer,75,"%A %B %d, %Y %H:%M:%S %Z",rome_info);
printf("%s, dst? = %d\n",rome_buffer,rome_info->tm_isdst);
printf("\n");

rome_ts = -1690768799;
rome_info = localtime(&rome_ts);
printf("Timestamp: %ld\n",rome_ts);
strftime(rome_buffer,75,"%A %B %d, %Y %H:%M:%S %Z",rome_info);
printf("%s, dst? = %d\n",rome_buffer,rome_info->tm_isdst);
printf("\n\n\n");


printf("My second transition:\n");

rome_ts = -1680483601;
rome_info = localtime(&rome_ts);
printf("Timestamp: %ld\n",rome_ts);
strftime(rome_buffer,75,"%A %B %d, %Y %H:%M:%S %Z",rome_info);
printf("%s, dst? = %d\n",rome_buffer,rome_info->tm_isdst);
printf("\n");

rome_ts = -1680483600;
rome_info = localtime(&rome_ts);
printf("Timestamp: %ld\n",rome_ts);
strftime(rome_buffer,75,"%A %B %d, %Y %H:%M:%S %Z",rome_info);
printf("%s, dst? = %d\n",rome_buffer,rome_info->tm_isdst);
printf("\n");

rome_ts = -1680483599;
rome_info = localtime(&rome_ts);
printf("Timestamp: %ld\n",rome_ts);
strftime(rome_buffer,75,"%A %B %d, %Y %H:%M:%S %Z",rome_info);
printf("%s, dst? = %d\n",rome_buffer,rome_info->tm_isdst);
printf("\n\n\n");

输出显示 localtime() 与我的转换时间一致：

我的第一次转换：时间戳：

-1690851601 1916 年 6 月 2 日星期五 23:59:59 CET，夏令时？ = 0

时间戳：-1690851600 六月星期六 1916 年 03 月 01:00:00 CEST，夏令时？ = 1

时间戳：-1690851599 六月星期六 1916 年 03 月 01:00:01 CEST，夏令时？ = 1

TimeandDate.com 的第一次转换：

时间戳：-1690768801 六月星期六 1916 年 1 月 3 日 23:59:59 CEST，夏令时？ = 1

时间戳：-1690768800 6 月 4 日星期日， 1916 00:00:00 CEST，夏令时？ = 1

时间戳：-1690768799 6 月 4 日星期日， 1916 00:00:01 CEST，夏令时？ = 1

我的第二次转换：时间戳：

-1680483601 1916 年 10 月 1 日星期日 00:59:59 CEST，夏令时？ = 1

时间戳：-1680483600 十月星期日 1916 年 01 月 00:00:00 CET，夏令时？ = 0

时间戳：-1680483599 十月星期日 1916 年 1 月 1 日 00:00:01 CET，夏令时？ = 0

【讨论】：