>perl -wMstrict -le
"my $test = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
 ;;
 my %inclusive_ranges = map { $_ => 1 } 7 .. 11, 18 .. 22;
 ;;
 my @excluded = grep ! $inclusive_ranges{$_}, 0 .. length($test) - 1;
 ;;
 my $str = $test;
 print qq{'$str'};
 ;;
 substr $str, $_, 1, '-' for @excluded;
 print qq{'$str'};
"
'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
'-------HIJKL------STUVW---'

##</code><code>##

>perl -wMstrict -le
"my $test = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
 ;;
 my %inclusive_ranges = map { $_ => 1 } 7 .. 11, 18 .. 22;
 ;;
 my $exclude_mask =
   join '',
   map $inclusive_ranges{$_} ? qq{\xFF} : qq{\x00},
   0 .. length($test) - 1
   ;
 ;;
 my $str = $test;
 print qq{'$str'};
 ;;
 $str &= $exclude_mask;
 $str =~ tr/\x00/-/;
 print qq{'$str'};
"
'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
'-------HIJKL------STUVW---'