The memory consumption of this is fixed to the total size of the domain regardless of the number of subranges it contains. Construction and addition of ranges is trivial. Lookup is O(1).

If the total range is somewhere in the bounds of sanity, then this is quick and easy and will often use less memory than the related hash or tree structure.

If the range is large, then you can use vec and reduce the memory requirement to 1/8 th.

It doesn't work well for real numbers--though it can approximate them.

#! perl -slw
use strict;
use List::Util qw[ reduce ]; $a = $b;

my $zones = reduce {
    my( $first, $last ) = split '-', $b;
    $last ||= $first; ## 1; corrected per [bmann]'s post below.
    substr( $a, $first, $last - $first + 1 ) = 'x' x ( $last - $first 
++ 1 );
    $a
} chr(0) x 1000, split ',', 
'10-374,376-379,382-385,388-499,530-534,541-543,618,619,700-704,707-70
+9';

print $zones =~ m[^.{$_}x] 
    ? "Found $_!" 
    : "$_ isn't there!" 
        for 9, 374, 375, 376, 999;
__END__
[12:03:42.74] P:\test>425464
9 isn't there!
Found 374!
375 isn't there!
Found 376!
999 isn't there!
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