Converting seconds to DD:HH:MM:SS

The _sensible approach seems the most sane way to me. That said, there are a few things to "fix".

First - what are the &'s doing there? Experienced perl programmer? As I said before, seeing that & is an indicator of low experience, not high experience, to me. It's an indicator of perl4 programming, which, granted, is a long time programming in perl, but does not equate to high amounts of good experience in modern perls. Unless, of course, it were used in a goto, or magic argument passing, or overriding prototypes. (Of course, the use of prototypes at all can be suspect.)

The first two options both take a parameter. Then ignore it. Your version uses your parameter. That's already a plus for your version.

And the sensible version clobbers $_. Bad. Maybe he meant to say:

  local $_ = shift;
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Finally, the subtraction is a bit funny. You get a funny lookin' number for the -1 time (-1 day plus 23 hours plus 59 minutes plus 59 seconds - technically correct, but may not be what you want). Perhaps what he meant was "$_ = int($_ / 60)". In that case, here's a slightly revamped sensible function:

sub sec_to_dhms_sensible2
{
    use integer;
    local $_ = shift;
    my ($d, $h, $m, $s);
    $s = $_ % 60; $_ /= 60;
    $m = $_ % 60; $_ /= 60;
    $h = $_ % 24; $_ /= 24;
    $d = $_;
    return ($d, $h, $m, $s);
}
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use integer;

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Your version shows the correct date/time for 2147483648(=2**31)seconds. Date::Calc version blows out w/ "out of range" error, and gam3's sec_to_ddmmss() shows "24855:20:45:52" (instead of "24855:03:14:08").

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sub seconds_to_dhms {
    my $t = shift;
    return int($t / 86400), (gmtime($t))[2, 1, 0];
}
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UPDATE: renamed function as per sauoq (I had copied it directly from the question.)

-- gam3
A picture is worth a thousand words, but takes 200K.

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sub sec_to_ddmmss { my $t = shift; return int($t / 86400), (gmtime($t))[2, 1, 0]; }
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This is clever, but I'd like to see it commented because at first glance, it might appear erroneous. It should be better named too. I'd probably call it seconds_to_dhms(). Yours is broken in two respects: 1) you missed 'hh' for hours and 2) the doubled letters imply that your return values are formatted to two digits.

-sauoq
"My two cents aren't worth a dime.";

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Recently I found myself having to convert an integer value (representing a number of seconds) into DD:HH:MM:SS

This question is relevant, because your colleague's solution uses Date::Calc::Delta_DHMS(), whose documentation describes it as follows:

This function returns the difference in days, hours, minutes and seconds between the two given dates with times.

not

localtime

Another point, before trying to compare the efficiency of your colleague's solution vs your own (which certainly looks simple), write some tests to make sure each is doing what you intend.

Jim Keenan

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#!/usr/bin/perl

use strict;
use warnings;

use Date::Calc qw(Delta_DHMS Time_to_Date);

my @secs = qw(1000 10000 100000 1000000 86400 86399 3600 3599 0 31394 
+2941 -2941 -86399);

for (@secs) {
  printf("%s%02d:%02d:%02d:%02d\n", $_ < 0 ? '-' : '', Delta_DHMS(Time
+_to_Date(0), Time_to_Date(abs($_))));
}
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Edit: Or, as a subroutine:

sub time_remaining {
  my $input_seconds = shift;
  return sprintf(("%s%02d:%02d:%02d:%02d", $input_seconds < 0 ? '-' : 
+'', Delta_DHMS(Time_to_Date(0), Time_to_Date(abs($input_seconds))));
}
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"In the meantime, I came up with my own solution (and I'm sure I'll get beaten up bigtime for this - but hey, I already had the DB handle open - so why not make use of it? ;)"

Certainly not a bad idea with a database application. The only thing you need to be aware of is that, the time that the database gives is not always the same as what the OS has. This might easily confuse people.

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If you want compact:

my @fields = ($secs % 60, ($secs /= 60) % 60, ($secs /= 60) % 24, int 
+($secs / 24));
print join ':', reverse @fields;
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However my Perl legalese is not up to assuring you that the calculation will be done in the correct order for all Perl implementations. :)

Perl is Huffman encoded by design.

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Never ignore the power of CPAN

use Date::Manip;
my $t = 234234324;
my ($d, $h, $m, $s)  = Delta_Format("+${t}seconds",'exact','%dh','%hv'
+,'%mv','%sv');
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Date::Calc

gloryhack

#!/usr/bin/perl

use strict;
use Date::Calc qw(Time_to_Date Delta_Days);

while(<DATA>){

warn join ":",
        map { sprintf "%02d", $_ }
        do {
          my @d = Time_to_Date($_);
          ( Delta_Days((Time_to_Date(0))[0..2], @d[0..2]), @d[3..5] )
        };

}

__DATA__
1000
10000
100000
1000000
86400
86399
3600
3599
0
-1
313942941
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I am curious to know the output from your DB for 2147483648.

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(I should point out that this is the first time I've used Benchmark, and also the first time I've attempted to write test code such as this, so my methodology may be a bit off. Also, the only changes I made to the other Monks code snippets was to make them into a subroutine if they weren't already.)

Read more... (4 kB)

%contenders = (
                'cw_sensible' => {
                                   '86399' => '0 0 0 0',
                                   '86400' => '0 0 0 0',
                                   '1' => '0 0 0 0',
                                   '2147483648' => '0 0 0 0',
                                   '0' => '0 0 0 0',
                                   '-2147483648' => '0 0 0 0',
                                   '-1' => '0 0 0 0',
                                   'code' => sub { "DUMMY" }
                                 },
                'snowhare' => {
                                '86399' => '0 23 59 59',
                                '86400' => '1 0 0 0',
                                '1' => '0 0 0 1',
                                '2147483648' => '24855 3 14 8',
                                '0' => '0 0 0 0',
                                '-2147483648' => '-24855 -3 -14 -8',
                                '-1' => '0 0 0 -1',
                                'code' => sub { "DUMMY" }
                              },
                'gam3' => {
                            '86399' => '0 23 59 59',
                            '86400' => '1 0 0 0',
                            '1' => '0 0 0 1',
                            '2147483648' => '24855 20 45 52',
                            '0' => '0 0 0 0',
                            '-2147483648' => '-24855 20 45 52',
                            '-1' => '0 23 59 59',
                            'code' => sub { "DUMMY" }
                          },
                'gloryhack' => {
                                 '86399' => '00:23:59:59',
                                 '86400' => '01:00:00:00',
                                 '1' => '00:00:00:01',
                                 '2147483648' => '',
                                 '0' => '00:00:00:00',
                                 '-2147483648' => '',
                                 '-1' => '-00:00:00:01',
                                 'code' => sub { "DUMMY" }
                               },
                'cw_silly' => {
                                '86399' => '0 23 59 59',
                                '86400' => '1 0 0 0',
                                '1' => '0 0 0 1',
                                '2147483648' => '-24855 -3 -14 -8',
                                '0' => '0 0 0 0',
                                '-2147483648' => '-24855 -3 -14 -8',
                                '-1' => '0 0 0 -1',
                                'code' => sub { "DUMMY" }
                              },
                'McDarren' => {
                                '86399' => '23:59:59',
                                '86400' => '24:00:00',
                                '1' => '00:00:01',
                                '2147483648' => '596523:14:08',
                                '0' => '00:00:00',
                                '-2147483648' => '-596523:14:08',
                                '-1' => '-00:00:01',
                                'code' => sub { "DUMMY" }
                              },
                'GrandFather' => {
                                   '86399' => '0:23:59:59',
                                   '86400' => '1:0:0:0',
                                   '1' => '0:0:0:1',
                                   '2147483648' => '24855:3:14:8',
                                   '0' => '0:0:0:0',
                                   '-2147483648' => '-24855:21:46:52',
                                   '-1' => '0:0:0:59',
                                   'code' => sub { "DUMMY" }
                                 },
                'Tanktulas' => {
                                 '86399' => '0 23 59 59',
                                 '86400' => '1 0 0 0',
                                 '1' => '0 0 0 1',
                                 '2147483648' => '-24855 -3 -14 -8',
                                 '0' => '0 0 0 0',
                                 '-2147483648' => '-24855 -3 -14 -8',
                                 '-1' => '0 0 0 -1',
                                 'code' => sub { "DUMMY" }
                               },
                'davidrw' => {
                               '86399' => '86399:86399:86399:86399',
                               '86400' => '86400:86400:86400:86400',
                               '1' => '01:01:01:01',
                               '2147483648' => '',
                               '0' => '00:00:00:00',
                               '-2147483648' => '',
                               '-1' => '',
                               'code' => sub { "DUMMY" }
                             }
              );
                Rate snowhare McDarren davidrw cw_sensible gloryhack c
+w_silly GrandFather  gam3 Tanktulas
snowhare       510/s       --     -83%    -97%        -98%      -99%  
+   -99%        -99% -100%     -100%
McDarren      3040/s     497%       --    -84%        -86%      -91%  
+   -92%        -95%  -98%      -98%
davidrw      19472/s    3721%     540%      --        -10%      -43%  
+   -47%        -67%  -85%      -87%
cw_sensible  21611/s    4141%     611%     11%          --      -37%  
+   -41%        -63%  -83%      -86%
gloryhack    34046/s    6581%    1020%     75%         58%        --  
+    -7%        -41%  -74%      -77%
cw_silly     36645/s    7092%    1105%     88%         70%        8%  
+     --        -37%  -72%      -76%
GrandFather  58163/s   11315%    1813%    199%        169%       71%  
+    59%          --  -55%      -61%
gam3        129947/s   25402%    4174%    567%        501%      282%  
+   255%        123%    --      -14%
Tanktulas   150334/s   29403%    4845%    672%        596%      342%  
+   310%        158%   16%        --
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Comments

Argument "exact" isn't numeric in numeric gt (>) at /usr/local/share/p
+erl/5.8.4/Date/Manip.pm line 1985.
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uninitiallised value

@secs

cw_sensible: Doesn't work at all (due to logic errors as pointed out by [id://Tanktalus])
[id://snowhare]: By far the slowest, but gives the correct results.
[id://gam3]: Quite quick, but fails on +/-(2^31).
[id://gloryhack]: Also fails on +/-(2^31). (This one didn't work at all at first - but then I changed the printf to sprintf and it did. Perhaps somebody can explain this to me?)
cw_silly: Failed on +(2^31).
[id://McDarren]: Works for all values, but one of the slowest.
[id://GrandFather]: Failed on -(2^31).
[id://Tanktalus]: By far the quickest, but fails on +(2^31).
[id://davidrw]: Doesn't seem to work at all.

Update:

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(Initially i was somewhat surprised that Tanktalus's version did not result in the right value for 2^31. I think it may be for you might not have perl compiled w/ USE_64_BIT_INT.)

A problem in the above benchmark is that not all the subroutines are returning the same type of result. I modified your above code ...

removed *_davidrw() from comparison as its result was quite odd;
removed *_snowhare() from comparison as it was the slowest (produced the same output as yours) ;
removed *_McDarren(), as i do not have mysql or equivalent DB installed currently;
edited cmpthese() somewhat;
made all the subs to return only a string;
grouped (non)module-using subs together.


"be consistent"
	PerlMonks