Derived from davido — dunno if it's more elegant or not:

use strict;
use warnings;

use List::Util qw(sum);


my $cgs = '10001011101010010101101000010101101011101111010100101010101
+0';

print  # prints 45 as does davido's solution
    sum
    map substr($cgs, $_->[1], $_->[2]-$_->[1]) =~ tr/0//,
    map [ split ],
    <DATA>
    ;


__DATA__
junk 5  15
junk 23 59
junk 18 34
junk 10 20
junk 9  19
junk 40 49
[download]

Update: Changed
    map scalar(substr($cgs, $_->[1], $_->[2]-$_->[1]) =~ tr/0//),
to
    map substr($cgs, $_->[1], $_->[2]-$_->[1]) =~ tr/0//,
(same result).