use open ':std', ':encoding(UTF-8)';  # UTF-8 terminal

my $s = "\xDC";
utf8::ugprade( $s );  # Use Unicode semantics
print lc($s), "\n";

##</code><code>##

use open ':std', ':encoding(UTF-8)';  # UTF-8 terminal
use feature 'unicode_strings';  # Or "use 5.012;"

my $s = "\xDC";
print lc($s), "\n";