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# You had
for ($l_count = 1; $l_count < $l_len; $l_count++)
...
# To build up a string like this you should be using the 'x' operator
my $lower = '9' x $l_len;

use constant MATCH => 1;  # Return value for good match
use constant FAIL  => 0;  # Retrun value for failed match
...

}