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Groups > comp.lang.c > #28982

Re: mktime

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On 12/06/2012 09:25 AM, Anders Wegge Keller wrote:
> 
>  According to the C2011 draft I have available, the values in the
> struct tm, passed to mktime(), are not restricted to the normalized
> ranges. (2.27.2.3 §2).
> 
>  Is this to be taken literally, such that any combination of values in
> the tm struct, that corresponds to something that can be expressed in
> a time_t is a valid input?

Yes. This feature, allows performance of date arithmetic. For instance,
take a struct tm that represents 2012-12-06 09:41, subtract 7 from
tm_mday, and pass it to mktime(), which should normalize that struct to
describe 2012-11-29 09:41. This is, in fact, the main thing I've ever
used mktime() for. mktime() has to know how many days there are in each
month, which years are leap years, what day of the week each date is; so
it saves me from having to write all that logic in my own code.

>  As I read the following paragrahp, that seem to be the case. Which
> lead me to think of exxtreme cases like tm_sec, tm_min, tm_hour,
> tm_mday and tm_mon all at INT_MAX, and tm_year set to a sufficiently
> large negative value. 
> 
>  Am I missing something, or would a conforming implementation have to
> handle this?

Yes, it would.
-- 
James Kuyper

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mktime Anders Wegge Keller <wegge@wegge.dk> - 2012-12-06 15:25 +0100
  Re: mktime James Kuyper <jameskuyper@verizon.net> - 2012-12-06 09:53 -0500
  Re: mktime Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-06 10:11 -0500
    Re: mktime Anders Wegge Keller <wegge@wegge.dk> - 2012-12-06 17:40 +0100
      Re: mktime Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-06 14:20 -0500
        Re: mktime Keith Thompson <kst-u@mib.org> - 2012-12-06 12:28 -0800
          Re: mktime Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-06 17:36 -0500
            Re: mktime Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-06 17:42 -0500
    Re: mktime Keith Thompson <kst-u@mib.org> - 2012-12-06 12:20 -0800
      Re: mktime Anders Wegge Keller <wegge@wegge.dk> - 2012-12-06 21:37 +0100
      Re: mktime "Heinrich Wolf" <invalid@invalid.invalid> - 2012-12-07 09:48 +0100
        Re: mktime James Kuyper <jameskuyper@verizon.net> - 2012-12-07 08:08 -0500
          Re: mktime "christian.bau" <christian.bau@cbau.wanadoo.co.uk> - 2012-12-07 09:23 -0800
            Re: mktime James Kuyper <jameskuyper@verizon.net> - 2012-12-07 13:14 -0500
            Re: mktime Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-07 13:46 -0500
            Re: mktime "Heinrich Wolf" <invalid@invalid.invalid> - 2012-12-07 19:59 +0100
            Re: mktime Robert Wessel <robertwessel2@yahoo.com> - 2012-12-07 15:50 -0600
        Re: mktime "Heinrich Wolf" <invalid@invalid.invalid> - 2012-12-07 21:39 +0100
          Re: mktime Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-07 17:17 -0500
            Re: mktime Keith Thompson <kst-u@mib.org> - 2012-12-07 17:50 -0800
              Re: mktime Eric Sosman <esosman@comcast-dot-net.invalid> - 2012-12-08 08:34 -0500
          Re: mktime pacman@kosh.dhis.org (Alan Curry) - 2012-12-07 22:44 +0000
            Re: mktime "Heinrich Wolf" <invalid@invalid.invalid> - 2012-12-08 10:31 +0100
              Re: mktime pacman@kosh.dhis.org (Alan Curry) - 2012-12-08 20:50 +0000
                Re: mktime "Heinrich Wolf" <invalid@invalid.invalid> - 2012-12-09 11:39 +0100
                Re: mktime pacman@kosh.dhis.org (Alan Curry) - 2012-12-09 19:47 +0000
                Re: mktime "Heinrich Wolf" <invalid@invalid.invalid> - 2012-12-10 09:51 +0100
                Re: mktime sla29970@gmail.com - 2012-12-09 08:41 -0800

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