use warnings;
use strict;

my @arr = (19,17,22,23,24,15,16,25..35);


sub find_missing {
        my @stuff = @_;
my @sorted_arr = sort {$a <=> $b} @stuff;

foreach my $num(0..$#sorted_arr-1) {

	my $current = $sorted_arr[$num];
	my $next    = $sorted_arr[++$num];
	my @missing =  ($current+1..$next-1);
	print "$current,";

	if ($next - $current != 1) {
		print "(missing: [@missing]),";
	} 
	
     }

print "$sorted_arr[-1]";
}


&find_missing(@arr);
	

##</code><code>##

C:\>perl findmissing.pl
15,16,17,(missing: [18]),19,(missing: [20 21]),22,23,24,25,26,27,28,29,30,31,32,33,34,35