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Re: efficient determination of in/out of hours

by soonix (Curate)
on Oct 17, 2013 at 13:52 UTC ( #1058632=note: print w/ replies, xml ) Need Help??


in reply to efficient determination of in/out of hours including Bank Holidays

next if $bh_start < time; # history
If the program ist started on a holiday (even 1 second past midnight), the routine will think it is a workday... I wanted to propose
... use integer; my $today = time / 86400 * 86400; # chop hours, minutes, seconds while (<DATA>) { # read bank holiday file ... next if $bh_start < $today; # history ... } ...
but this doesn't work correctly, either, because time is in seconds since some 1970-01-01 UTC...


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Re^2: efficient determination of in/out of hours
by Random_Walk (Parson) on Oct 17, 2013 at 15:45 UTC

    Nice catch, thanks. Perhaps something like this will fix it

    my $now = time; my $today = $now - ($now % 86400); while (<DATA>) { # read bank holiday file ... next if $bh_start < $today; # history ... } ...

    I gotta run home now, will test it really works later

    Update

    Sadly it does not work. It looks lie POSIX mktime is based on GMT, localtime, of course is not. I added the above change, plus a bit of printing and a bank holiday for today (localtime now: 2116, GMT 2016) running the code it does skip todays bank hol (17th Oct 2013)

    start of day (epoch based):Thu Oct 17 01:00:00 2013 Bank Hols Mon Oct 21 00:00:00 2013 Mon Feb 3 00:00:00 2014

    Is there a better way to get timezone offset than to mktime for epoch + 1 day and comapare to localtime for the same? Can I trust the environment, or is there a magic Perl var?

    Cheers,
    R.

    Pereant, qui ante nos nostra dixerunt!
      That's mathematically the same. (If 86400 were a power of 2, the most efficient way 'd be >> and <<.) However time and mktime refer to different timezones. Unless you happen to be in Iceland, there are some hours when this works wrong...
      Update: I posted this while you updated your post :-)
      I'm not at my computer, but perhaps something like mktime(gmtime) for determining today's midnight could work...

        The core of the problem is that I am incorrectly storing bank holiday start points in epoch seconds based on UTC0. Of course they actualy start at localtime == 00:00:00. I think I need to revise the code to store bank hols as (YYYY-1900):MM:DD, then compare to the appropriate fields of locatime($epoch).

        original node updated with fixed code.


        Cheers,
        R.

        Pereant, qui ante nos nostra dixerunt!

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