Hello Monks, I am pretty much new to Perl and writing a log parsing application,
where i need to compare the time stamp of every line in the log file to the previous line.
I tried using the DateCalc function of Date::Manip , but its taking ever to complete a file with some 65000 lines.
So thought of writing my own function. And below is the code snippet. 

my (@d_in_m) = ( 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 );

my $t1 = "2009-04-12 23:59:55 PM";
my $t2 = "2009-03-30 00:00:02 PM";

my @date1 = split( /-| |:/, $t1 );
my @date2 = split( /-| |:/, $t2 );

my $delta_sec = 0;

sub month_delta {
    my ( $from_month, $to_month, $from_year, $to_year ) = @_;
    my $delta = 0;
    if ( ( $to_year > $from_year ) && ( $to_month > $from_month ) ) {
        $delta += ( $to_year - $from_year ) * 31536000;
    }
    
    for (
        my $i = ( ( $from_month + 1 ) > 12 ) ? 1 : ( $from_month + 1 )
+ ;
        $i < $to_month ;
        $i++
      )
    {
        $delta += ( $d_in_m[$i] * 86400 );
    }
    return $delta;
}



my ( $date1_ref, $date2_ref ) = ( \@date1, \@date2 );


    if(($date2[0]<= $date1[0]) && ($date2[1]< $date1[1]) ){
        print "swapping the date \n";
    ($date1_ref, $date2_ref) = ($date2_ref, $date1_ref);
    }


    if (
        $date2_ref->[0] . $date2_ref->[1] eq $date1_ref->[0] . $date1_
+ref->[1] )
    {
        $delta_sec = $date2_ref->[5] - $date1_ref->[5];
        $delta_sec += ( $date2_ref->[4] - $date1_ref->[4] ) * 60;
        $delta_sec += ( $date2_ref->[3] - $date1_ref->[3] ) * 3600;
        $delta_sec += ( $date2_ref->[2] - $date1_ref->[2] ) * 86400;
    }
    elsif ( $date1_ref->[2] <= $d_in_m[ $date1_ref->[1] ] ) {

        $delta_sec = $date2_ref->[5] - $date1_ref->[5];
        $delta_sec += ( $date2_ref->[4] - $date1_ref->[4] ) * 60;
        $delta_sec += ( $date2_ref->[3] - $date1_ref->[3] ) * 3600;
        $delta_sec += ( $date2_ref->[2] ) * 86400;
        $delta_sec +=
          ( $d_in_m[ $date1_ref->[1] ] - $date1_ref->[2] ) * 86400 +
          month_delta(
            $date1_ref->[1], $date2_ref->[1],
            $date1_ref->[0], $date2_ref->[0]
          );
    }
    else {
        print "Seems to be a invalid comparison delta b/w $t1 and $t2\
+n";
    }

    print "!!!! Delta b/w $t1 and $t2 is " . $delta_sec . "\n";

[download]


I have tested this for several combinations and it seems to work.
Yet to handle the leap year case which is any ways of least needed for my program.

This is much more faster than the Date::Manip module.

Please look at this and let me know if i can make it more optimized or missed out any scenarios.


If needed you can use this code also :-)


Thanks

In reply to Code to calculate Delta b/w two dates in seconds by snra_perl

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