use locale;
use POSIX qw(locale_h);
use POSIX;

use Encode;

my $old_lcall = setlocale(LC_ALL);
my $old_ctype = setlocale(LC_CTYPE);
setlocale(LC_ALL,"cs_CZ.utf8");
setlocale(LC_CTYPE,"cs_CZ.utf8");

# ...the $text variable has also been encoded as UTF-8 (the 
# hyphenated version), using the encode function provided 
# by use Encode;

my @letters = split //, $text;

# and at the end of the code, set the locales back:
setlocale(LC_ALL, $old_lcall);
setlocale(LC_CTYPE, $old_ctype);