Acessing the "time" Part of time_t Value

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  • Mike Copeland
    #1

    Acessing the "time" Part of time_t Value

    How do I mask out all but the _time_ components of a time_t value?
    Specifically, I have the following:
    time_t wTime = 1226764757;
    I happen to know that this is November 16, 2008 @ 8:59:17, but I have
    many other such items from which I want to use only the _time_ portion
    (e.g. 8:59:17). How do I eliminate the "date" portions of either the
    time_t value or the number I assign to it? TIA
    Tags: None
    • miso.liptak
      #2
      Re: Acessing the "time&quot ; Part of time_t Value

      On Nov 20, 8:03 am, mrc2...@cox.net (Mike Copeland) wrote:
         How do I mask out all but the _time_ components of a time_t value? 
      Specifically, I have the following:
              time_t wTime = 1226764757;
         I happen to know that this is November 16, 2008 @ 8:59:17, but I have
      many other such items from which I want to use only the _time_ portion
      (e.g. 8:59:17).  How do I eliminate the "date" portions of either the
      time_t value or the number I assign to it?  TIA
      Is number of seconds since midnight what you want? time(0) % 86400?
      m.

        Comment

        • Pete Becker
          #3
          Re: Acessing the "time&quot ; Part of time_t Value

          On 2008-11-20 02:03:33 -0500, mrc2323@cox.net (Mike Copeland) said:
          How do I mask out all but the _time_ components of a time_t value?
          Specifically, I have the following:
          time_t wTime = 1226764757;
          I happen to know that this is November 16, 2008 @ 8:59:17, but I have
          many other such items from which I want to use only the _time_ portion
          (e.g. 8:59:17). How do I eliminate the "date" portions of either the
          time_t value or the number I assign to it? TIA
          Use gmtime() or localtime() to convert it to a tm.

          --
          Pete
          Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
          Standard C++ Library Extensions: a Tutorial and Reference
          (www.petebecker.com/tr1book)

            Comment

            • Pete Becker
              #4
              Re: Acessing the "time&quot ; Part of time_t Value

              On 2008-11-20 02:56:08 -0500, "miso.lipta k" <miso.liptak@gm ail.comsaid:
              On Nov 20, 8:03 am, mrc2...@cox.net (Mike Copeland) wrote:
              >   How do I mask out all but the _time_ components of a time_t value?
               
              >Specifically , I have the following:
              >        time_t wTime = 1226764757;
              >   I happen to know that this is November 16, 2008 @ 8:59:17, but I h
              ave
              >many other such items from which I want to use only the _time_ portion
              >(e.g. 8:59:17).  How do I eliminate the "date" portions of either the
              >time_t value or the number I assign to it?  TIA
              >
              Is number of seconds since midnight what you want? time(0) % 86400?
              m.
              The requirement (from the C standard) is that time_t is an "arithmetic
              type capable of representing times ...". That's all. It doesn't have to
              represent seconds, nor does it have to be based on midnight.

              --
              Pete
              Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
              Standard C++ Library Extensions: a Tutorial and Reference
              (www.petebecker.com/tr1book)

                Comment

                • James Kanze
                  #5
                  Re: Acessing the &quot;time&quot ; Part of time_t Value

                  On Nov 20, 8:56 am, "miso.lipta k" <miso.lip...@gm ail.comwrote:
                  On Nov 20, 8:03 am, mrc2...@cox.net (Mike Copeland) wrote:
                  How do I mask out all but the _time_ components of a time_t
                  value? Specifically, I have the following:
                  time_t wTime = 1226764757;
                  I happen to know that this is November 16, 2008 @ 8:59:17,
                  but I have many other such items from which I want to use
                  only the _time_ portion (e.g. 8:59:17). How do I eliminate
                  the "date" portions of either the time_t value or the number
                  I assign to it? TIA
                  Is number of seconds since midnight what you want? time(0) %
                  86400?
                  That depends on how precise and how portable you have to be.
                  Not all days have exactly 86400 seconds, and time_t can be any
                  numeric type, with any representation---if it uses the
                  representation that was current in MS-DOS, your results are
                  meaningless, and if it is a double, your solution won't even
                  compile. (But for a lot of uses, it's adequate. It's what I
                  currently do---but in my case, even if I'm a minute or so off,
                  it's no big deal, and I only have to support
                  Unix-likes---Solaris and Linux.)

                  --
                  James Kanze (GABI Software) email:james.kan ze@gmail.com
                  Conseils en informatique orientée objet/
                  Beratung in objektorientier ter Datenverarbeitu ng
                  9 place Sémard, 78210 St.-Cyr-l'École, France, +33 (0)1 30 23 00 34

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