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PERL Countdown Timer

by vicpylon (Initiate)
on Nov 15, 2004 at 19:04 UTC ( #407906=perlquestion: print w/ replies, xml ) Need Help??
vicpylon has asked for the wisdom of the Perl Monks concerning the following question:

I am but a humble seeker of wisdom and respectfully ask the following. I have to come up with a timer that counts down from a user selected time (1-12 hours) and then produces a message (FINISHED). Problem is I can't seem to get my head around how to do it. Yes, I am a rookie, but this is giving me a headache. Any help is appreciated. Vic

Comment on PERL Countdown Timer
Re: PERL Countdown Timer
by CountZero (Bishop) on Nov 15, 2004 at 19:28 UTC
    Three steps should do the trick:
    1. Calculate how many seconds the countdown should run and store this in $seconds.
    2. sleep $seconds;
    3. print "Finished"

    CountZero

    "If you have four groups working on a compiler, you'll get a 4-pass compiler." - Conway's Law

Re: PERL Countdown Timer
by ikegami (Pope) on Nov 15, 2004 at 19:29 UTC

    (A quick aside: The language is Perl, not PERL.)

    use strict; use warnings; my $countdown = 1*60*60; # in secs. $| = 1; my $beg_time = time; my $end_time = $beg_time + $countdown; for (;;) { my $time = time; last if ($time >= $end_time); printf("\r%02d:%02d:%02d", ($end_time - $time) / (60*60), ($end_time - $time) / ( 60) % 60, ($end_time - $time) % 60, ); sleep(1); } print("\rKABOOM!!!!\n");

    Below is an alternative, but it will drift. That means that if you count down for 12 hours, it may take 12 hours and 5 minutes, or even much more than that, depending on CPU utilisation of other processes and more. I'm providing it as an example of what you should NOT do.

    Bad code:

      A minor nit-pick, you need a
      $|++;
      in your code, or the timer will not update the display properly.

      I'm not really a human, but I play one on earth. flash japh
        oops, right, you need that on non-Windows systems. I tested my code in Windows, which line-flushes on \r and \n (as opposed to just on \n).
      I put it in a simple sub. Easy to adjust if you want to include additional parameters such as a pre or post message.
      countdown(10); sub countdown($) { #countdown(seconds); my ($duration) = @_; my $end_time = time + $duration; my $time = time; while ($time < $end_time) { $time = time; printf("\r%02d:%02d:%02d", ($end_time - $time) / (60*60), ($en +d_time - $time) / (60) % 60,($end_time - $time) % 60); #00:00:10 $|++; sleep 1; } }

      countdown(10, "before", "after"); sub countdown($$$) { #countdown(seconds, "premessage", "postmessage"); my ($duration, $premessage, $postmessage) = @_; my $end_time = time + $duration; my $time = time; while ($time < $end_time) { $time = time; printf("\r%s %02d:%02d:%02d %s", $premessage, ($end_time - $ti +me) / (60*60), ($end_time - $time) / (60) % 60,($end_time - $time) % +60, $postmessage); #before 00:00:10 after $|++; sleep 1; } }
Re: PERL Countdown Timer
by TedPride (Priest) on Nov 16, 2004 at 15:39 UTC
    Here you go. I included some error checking in case someone mixed letters in with the number, or left out the numerical part entirely:
    use strict; use warnings; print "How long should I sleep, in hours? "; my $wait = <STDIN>; ($wait) = $wait =~ /(\d+)/; $wait -= 0; my $end = time() + $wait * 3600; sleep 1 while time() < $end; print "FINISHED";

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