Converting the hh24:mm format into seconds since midnight allows for greater simplification and modularisationg of the code. 
use strict;
use Data::Dumper;

#################################################
#converts a string hh24:mm into seconds equivalent since midnight

sub convert_to_seconds {
    my $time = shift;
    my ($hours, $minutes) = split ':', $time;
    return $hours * 3600 + $minutes * 60;
}
#################################################
#converts a seconds since midnight into hh24:mm format

sub convert_to_hh24mm {

    my $time = shift;
    my $hours = int ($time / 3600);
    my $minutes = ($time % 3600) / 60;
    return sprintf("%02d:%02d", $hours, $minutes);
}
#################################################
#takes a begin and end time (in seconds since midnight)
#and an interval (in seconds as well) as arguments

sub generate_intervals {

    my ($begin, $end, $interval) = @_;
    my @intervals;

    while ($end > $begin) {
        push @intervals, $begin;
        $begin += $interval;
    }

    return @intervals;

}

#################################################
# M A I N
#
my $begintime = '18:20';
my $endtime = '22:30';

my $interval = 15;

my @intervals = generate_intervals( convert_to_seconds($begintime), co
+nvert_to_seconds($endtime), $interval * 60);


foreach (@intervals){
    print Dumper(convert_to_hh24mm($_) );
}

[download]
This outputs :

E:\>perl -w test.pl
$VAR1 = '18:20';
$VAR1 = '18:35';
$VAR1 = '18:50';
$VAR1 = '19:05';
$VAR1 = '19:20';
$VAR1 = '19:35';
$VAR1 = '19:50';
$VAR1 = '20:05';
$VAR1 = '20:20';
$VAR1 = '20:35';
$VAR1 = '20:50';
$VAR1 = '21:05';
$VAR1 = '21:20';
$VAR1 = '21:35';
$VAR1 = '21:50';
$VAR1 = '22:05';
$VAR1 = '22:20';

Jorg

"Do or do not, there is no try" -- Yoda

In reply to Re: Generating basic time intervals between two times by jorg
in thread Generating basic time intervals between two times by ryan

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