use Encode qw( encode_utf8 );
my $x = chr(1 << 63);
my @Unsorted = ( 'Dog', 'Cat', 'Bird', undef, $x, 'Elephant', undef, 'Lizard' );

##</code><code>##

S:\Steve\Dev\PerlMonks\P-2017-06-12@0734-sort-undef>perl .\sort011.pl
-------------------------------------------------------------------------------
Original:
-------------------------------------------------------------------------------
Dog
Cat
Bird
(undef)
Wide character in print at .\sort011.pl line 58.
 ÇêÇÇÇÇÇÇÇÇÇÇ
Elephant
(undef)
Lizard
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
Custom Sort:
-------------------------------------------------------------------------------
Bird
Cat
Dog
Elephant
Lizard
(undef)
(undef)
Wide character in print at .\sort011.pl line 58.
 ÇêÇÇÇÇÇÇÇÇÇÇ
-------------------------------------------------------------------------------

S:\Steve\Dev\PerlMonks\P-2017-06-12@0734-sort-undef>