Re: time functions weirdness

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From	Keith Thompson <kst-u@mib.org>
Newsgroups	comp.lang.c
Subject	Re: time functions weirdness
Date	Sat, 17 Sep 2016 17:04:02 -0700
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Robert Latest <boblatest@yahoo.com> writes:
> the task is simple: Convert a time string to a time_t and back. I'm not even
> concerned with timezones, I want everything to be in UTC. But for some
> reason it just doesn't work and I don't know why. Is it possible that
> mktime()'s and gmtime()'s notions of the UNIX epoch differ by one hour?
[...]

localtime() converts a time_t value to a struct tm value representing
a local time.  gmtime() converts a time_t value to a struct tm
value representing a UTC time.

mktime() is essentially the inverse of localtime(); it converts
a struct tm value representing a local time to a time_t value.
There is no inverse of the gmtime() function.

This is IMHO quite unfortunate, and I don't know why something like a
mktime_utc() function (perhaps with a better name) was never added
to the standard.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"

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time functions weirdness Robert Latest <boblatest@yahoo.com> - 2016-09-17 17:35 +0000
  Re: time functions weirdness Robert Latest <boblatest@yahoo.com> - 2016-09-17 17:38 +0000
  Re: time functions weirdness "James R. Kuyper" <jameskuyper@verizon.net> - 2016-09-17 14:26 -0400
    Re: time functions weirdness Robert Latest <boblatest@yahoo.com> - 2016-09-17 20:26 +0000
      Re: time functions weirdness "James R. Kuyper" <jameskuyper@verizon.net> - 2016-09-17 17:21 -0400
        Re: time functions weirdness Keith Thompson <kst-u@mib.org> - 2016-09-17 16:54 -0700
          Re: time functions weirdness "James R. Kuyper" <jameskuyper@verizon.net> - 2016-09-17 18:00 -0400
          Re: time functions weirdness Ian Collins <ian-news@hotmail.com> - 2016-09-18 10:45 +1200
      Re: time functions weirdness Keith Thompson <kst-u@mib.org> - 2016-09-17 17:24 -0700
        Re: time functions weirdness Robert Latest <boblatest@yahoo.com> - 2016-09-18 06:25 +0000
          Re: time functions weirdness Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-18 20:40 +0100
            Re: time functions weirdness supercat@casperkitty.com - 2016-09-18 16:00 -0700
  Re: time functions weirdness Keith Thompson <kst-u@mib.org> - 2016-09-17 17:04 -0700

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