sub range_populate { my ($max, $range) = @_; my @range = (); if ($range eq 'a') { return \@{[0..$max]}; } elsif ($range !~ /[-,]/) { push @range, $range; } else { my @mini = split /,/, $range; for (@mini) { return undef if /-.*?-/; # 1 dash per subsection, e.g., "2-6-9, 24" is invalid if ( !/-/ ) { push @range, $_; } else { return undef unless /(\d+)-(\d+)/; return undef unless $1 < $2; push @range, ($1..$2); } } } return undef if $#range == -1; for (@range) { return undef unless ($_ >= 0 && $_ <= $max); } return \@range; } # example my $num_messages = 10; my $sample_range = '3-6,9'; my $rng_ref = &range_populate ($num_messages, $sample_range); # returns reference to array (3, 4, 5, 6, 9)