days between dates

StayTheCourse has asked for the wisdom of the Perl Monks concerning the following question:

Unix and my pc give different answers when running this code. pc returns 39843 and unix returns 41338 and unix gives the correct answer.

#!/bin/perl58
use Time::Local;
$date='3/5/2013';
$dbt=&daysbetween('1/1/1904',$date);
$dbt += 1462;# for 1900-1903 plus 2 days
warn "$dbt $date and 1/1/1900\n";
#---------------------------------------------------------------------
+--------
sub daysbetween {

    my($dte,$dte1)= @_;

    my ( $mo, $dy, $yr) = split /\//, $dte;
    my ( $mo1, $dy1, $yr1) = split /\//, $dte1;

    $mo = $mo - 1;
    $mo1 = $mo1 - 1;

    if($dy > 31 || $dy < 1){
        warn "$transid $dte $dte1\n";
        return 1000000;
    }
    if($dy1 > 31 || $dy1 < 1){
        warn "$transid $dte $dte1\n";
        return 1000000;
    }
    if($mo > 11 || $mo < 0){
        warn "$transid $dte $dte1\n";
        return 1000000;
    }
    if($mo1 > 11 || $mo1 < 0){
        warn "$transid $dte $dte1\n";
        return 1000000;
    }
    if($yr > 2037){
        warn "$transid $dte $dte1\n";
        return 1000000;
    }
    if($yr1 > 2037){
        warn "$transid $dte $dte1\n";
        return 1000000;
    }
    my $ltime = timelocal ( 0, 0, 1, $dy, $mo, $yr );
    my $ltime1 = timelocal ( 0, 0, 1, $dy1, $mo1, $yr1 );
    my $days=sprintf("%.0f",($ltime1-$ltime)/86400);
    
    return $days;
}
#---------------------------------------------------------------------
+--------
[download]

Comment on days between dates Download Code

Replies are listed 'Best First'.
Re: days between dates by Ratazong (Monsignor) on Mar 15, 2013 at 14:27 UTC
Hi! If you are doing date-calculations, I strongly recommend not to re-invent the wheel, but to use a standard module. I have very good experiences with Date::Calc, which provides a function called Delta_Days. And which is consistent on any platform. `use Date::Calc qw (Delta_Days); print Delta_Days (1904,1,1, 2013,3,5) + 1462 , "\n";` [download] HTH, Rata	[reply] [d/l]
Re: days between dates by SuicideJunkie (Vicar) on Mar 15, 2013 at 14:22 UTC
Your first step should be to print out the contents of your variables at each step and see where your assumptions become false. The zeroth step should be to use a CPAN module to do the date math for you since it will handle all the edge cases you missed.	[reply]
Re: days between dates by choroba (Cardinal) on Mar 15, 2013 at 14:45 UTC
Another CPAN module to give the answer: Date::Manip. `#!/usr/bin/perl use strict; use warnings; use Date::Manip; my $delta = DateCalc(ParseDate('1/1/1904'), ParseDate('3/5/2013')); print 1462 + Delta_Format($delta, 0,'%dt'), "\n";` [download] لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply] [d/l]
Re: days between dates by vagabonding electron (Curate) on Mar 16, 2013 at 15:35 UTC
Yet another option could be with Time::Piece (a core module now): `#!/usr/bin/perl use strict; use warnings; use Time::Piece; my $datf = Time::Piece->strptime("1/1/1904", "%d/%m/%Y"); my $datt = Time::Piece->strptime("5/3/2013", "%d/%m/%Y"); my $diff = $datt - $datf; my $result = $diff->days + 1462; print "$result days\n";` [download] This prints "41338 days".	[reply] [d/l]
Re: days between dates by pvaldes (Chaplain) on Mar 15, 2013 at 15:15 UTC
Maybe $dte1 is not what you think. Check: `my($dte,$dte1)= @_;` try with: `my $dte = $_[0]; my $dte1 = $_[1]; print "dte is :",$dte," and dte1 is: ",$dte1;` [download]	[reply] [d/l] [select]


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