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

Hello Monks,

i have a question here regarding to calculate the minutes difference between two dates. i have written a code here, but i know it's not very accurate, because i assume every month is 30 days and 365 days in a year (it goes very wrong when calculate the dates for example: 2007-12-31 16:50:00;2008-1-1 04:24:00;), anyone know there is a perl module can calculate the accurate minuets between two dates ?

#!/usr/bin/perl
use strict;
use warnings;

#Using perl package
use Date::Calc qw(Delta_YMDHMS);       
use Date::Calc qw(Add_Delta_DHMS);     

#subroutine: rounding no
sub round($);                          

while (<TEMP>) 
{

  my @line=split(";");
  my @start_time=($line[3]=~/(\d+)-(\d+)-(\d+)\s(\d+):(\d+):(\d+)/);  
+ #parsing the start time
  my @stop_time=($line[4]=~/(\d+)-(\d+)-(\d+)\s(\d+):(\d+):(\d+)/);   
+ #parsing the stop time
    my @diff=Delta_YMDHMS(@start_time,@stop_time);                    
+                                   #calculate diff in YMDHMS
   my($yyyy,$m,$d,$hh,$mm,$ss)=@diff;
  $min_diff=($yyyy*365*24*60+$m*30*24*60+$d*24*60+$hh*60+$mm*1+$ss*0);
+                     #convert to mins
  $interval=round($min_diff/15);                                      
+                              #get the interval
  print "minutes difference between two dates are: $min_diff";
}


sub round($) {
    my($number) = shift;
    return int($number + .5);
}

[download]
thanks,

Replies are listed 'Best First'.
Re: Calculate time difference between two dates
by ikegami (Patriarch) on Oct 06, 2009 at 19:46 UTC

    It's impossible to know the different in minutes without knowing the timezone of the times.

    I use DateTime 

    #!/usr/bin/perl

use strict;
use warnings;

use DateTime                   qw( );
use DateTime::Format::Strptime qw( );

my $format = DateTime::Format::Strptime->new(
    pattern => '%Y-%m-%d %H:%M:%S',
);

my $start = $format->parse_datetime( '2007-12-31 16:50:00' );
my $stop  = $format->parse_datetime( '2008-1-1 04:24:00' );

$_->set_time_zone('local') for $start, $stop;

print( $start->delta_ms($stop)->in_units('minutes'), "\n" );  # 694

    [download]
[reply]
[d/l]
Re: Find minutes difference between two dates
by Anonymous Monk on Oct 06, 2009 at 20:36 UTC
    thank you for ikegami and the anonymous.

    ikegami: is it possible to use your method to parse date string from a csv file. coz i have lots of dates need to be calculated. can i use something like: 

    while ($line=<TEMP>) 
{
 my $start = $format->parse_datetime( $line[3] );
 my $stop  = $format->parse_datetime( $line[4] );
}

    [download]

    the anonymous: i have tried your code, however get the following error:

    Month '12' out of range 0..11 at test.perl line 33

    any suggestions for correction ?

    many thanks guys ! Simon
[reply]
[d/l]
[select]

      can i use something like:

      Yes.

      Month '12' out of range 0..11 at test.perl line 33

      Subtract 1 from the month and 1900 from the year before passing to timelocal.

[reply]
[d/l]
      any suggestions for correction ?

      Oh. I forgot that timelocal expects the month parameter to be in the range of 0..11, 0 being January and 11 being december.

      my $start_time = timelocal($start_time[5], $start_time[4], $start_time
+[3], $start_time[2], $start_time[1]-1, $start_time[0]);

  my $end_time = timelocal($end_time[5], $end_time[4], $end_time[3], $
+end_time[2], $end_time[1]-1, $end_time[0]);

      [download]
      Note the -1's.

      Ikegami's solution is much better when it comes to readability and maintainability, but mine is probably cheaper.
[reply]
[d/l]
Re: Find minutes difference between two dates
by Anonymous Monk on Oct 06, 2009 at 19:50 UTC
    For example:

    use Time::Local;

while (<>) {
  my @line=split(";");
  my @start_time=($line[3]=~/(\d+)-(\d+)-(\d+)\s(\d+):(\d+):(\d+)/);  
+ #parsing the start time
  my @stop_time=($line[4]=~/(\d+)-(\d+)-(\d+)\s(\d+):(\d+):(\d+)/);  #
+parsing the stop time

  my $start_time = timelocal($start_time[5], $start_time[4], $start_ti
+me[3], $start_time[2], $start_time[1], $start_time[0]);

  my $end_time = timelocal($end_time[5], $end_time[4], $end_time[3], $
+end_time[2], $end_time[1], $end_time[0]);

  my $min_diff = sprintf("%.0f", ($end_time - $start_time) / 60);

  print $min_diff."\n";
}

    [download]
    (untested code)

    Also, your rounding function is weird. Use (s)printf if you want correctly rounded numbers.
[reply]
[d/l]

      Also, your rounding function is weird. Use (s)printf if you want correctly rounded numbers.

      Not weird, and definitely cheaper than building a string then converting the string into a number.

[reply]

Back to Seekers of Perl Wisdom