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PERLUNICOOK(1pm)       Perl Programmers Reference Guide       PERLUNICOOK(1pm)


       perlunicook - cookbookish examples of handling Unicode in Perl


       This manpage contains short recipes demonstrating how to handle common
       Unicode operations in Perl, plus one complete program at the end. Any
       undeclared variables in individual recipes are assumed to have a
       previous appropriate value in them.


   X 0: Standard preamble
       Unless otherwise notes, all examples below require this standard
       preamble to work correctly, with the "#!" adjusted to work on your

        #!/usr/bin/env perl

        use utf8;      # so literals and identifiers can be in UTF-8
        use v5.12;     # or later to get "unicode_strings" feature
        use strict;    # quote strings, declare variables
        use warnings;  # on by default
        use warnings  qw(FATAL utf8);    # fatalize encoding glitches
        use open      qw(:std :encoding(UTF-8)); # undeclared streams in UTF-8
        use charnames qw(:full :short);  # unneeded in v5.16

       This does make even Unix programmers "binmode" your binary streams, or
       open them with ":raw", but that's the only way to get at them portably

       WARNING: "use autodie" (pre 2.26) and "use open" do not get along with
       each other.

   X 1: Generic Unicode-savvy filter
       Always decompose on the way in, then recompose on the way out.

        use Unicode::Normalize;

        while (<>) {
            $_ = NFD($_);   # decompose + reorder canonically
        } continue {
            print NFC($_);  # recompose (where possible) + reorder canonically

   X 2: Fine-tuning Unicode warnings
       As of v5.14, Perl distinguishes three subclasses of UTFX8 warnings.

        use v5.14;                  # subwarnings unavailable any earlier
        no warnings "nonchar";      # the 66 forbidden non-characters
        no warnings "surrogate";    # UTF-16/CESU-8 nonsense
        no warnings "non_unicode";  # for codepoints over 0x10_FFFF

   X 3: Declare source in utf8 for identifiers and literals
       Without the all-critical "use utf8" declaration, putting UTFX8 in your
       literals and identifiers wonXt work right.  If you used the standard
       preamble just given above, this already happened.  If you did, you can
       do things like this:

        use utf8;

        my $measure   = "Aangstroem";
        my @Xsoft     = qw( cp852 cp1251 cp1252 );
        my @XXXXXXXXX = qw( XXXX  XXXXX );
        my @X        = qw( koi8-f koi8-u koi8-r );
        my $motto     = "X X X"; # FAMILY, GROWING HEART, DROMEDARY CAMEL

       If you forget "use utf8", high bytes will be misunderstood as separate
       characters, and nothing will work right.

   X 4: Characters and their numbers
       The "ord" and "chr" functions work transparently on all codepoints, not
       just on ASCII alone X nor in fact, not even just on Unicode alone.

        # ASCII characters

        # characters from the Basic Multilingual Plane

        # beyond the BMP
        ord("X")               # MATHEMATICAL ITALIC SMALL N

        # beyond Unicode! (up to MAXINT)

   X 5: Unicode literals by character number
       In an interpolated literal, whether a double-quoted string or a regex,
       you may specify a character by its number using the "\x{HHHHHH}"

        String: "\x{3a3}"
        Regex:  /\x{3a3}/

        String: "\x{1d45b}"
        Regex:  /\x{1d45b}/

        # even non-BMP ranges in regex work fine

   X 6: Get character name by number
        use charnames ();
        my $name = charnames::viacode(0x03A3);

   X 7: Get character number by name
        use charnames ();
        my $number = charnames::vianame("GREEK CAPITAL LETTER SIGMA");

   X 8: Unicode named characters
       Use the "\N{charname}" notation to get the character by that name for
       use in interpolated literals (double-quoted strings and regexes).  In
       v5.16, there is an implicit

        use charnames qw(:full :short);

       But prior to v5.16, you must be explicit about which set of charnames
       you want.  The ":full" names are the official Unicode character name,
       alias, or sequence, which all share a namespace.

        use charnames qw(:full :short latin greek);

        "\N{MATHEMATICAL ITALIC SMALL N}"      # :full
        "\N{GREEK CAPITAL LETTER SIGMA}"       # :full

       Anything else is a Perl-specific convenience abbreviation.  Specify one
       or more scripts by names if you want short names that are script-

        "\N{Greek:Sigma}"                      # :short
        "\N{ae}"                               #  latin
        "\N{epsilon}"                          #  greek

       The v5.16 release also supports a ":loose" import for loose matching of
       character names, which works just like loose matching of property
       names: that is, it disregards case, whitespace, and underscores:

        "\N{euro sign}"                        # :loose (from v5.16)

       Starting in v5.32, you can also use

        qr/\p{name=euro sign}/

       to get official Unicode named characters in regular expressions.  Loose
       matching is always done for these.

   X 9: Unicode named sequences
       These look just like character names but return multiple codepoints.
       Notice the %vx vector-print functionality in "printf".

        use charnames qw(:full);
        printf "U+%v04X\n", $seq;

   X 10: Custom named characters
       Use ":alias" to give your own lexically scoped nicknames to existing
       characters, or even to give unnamed private-use characters useful

        use charnames ":full", ":alias" => {
            ecute => "LATIN SMALL LETTER E WITH ACUTE",
            "APPLE LOGO" => 0xF8FF, # private use character

        "\N{APPLE LOGO}"

   X 11: Names of CJK codepoints
       Sinograms like XXXX come back with character names of "CJK UNIFIED
       IDEOGRAPH-6771" and "CJK UNIFIED IDEOGRAPH-4EAC", because their XnamesX
       vary.  The CPAN "Unicode::Unihan" module has a large database for
       decoding these (and a whole lot more), provided you know how to
       understand its output.

        # cpan -i Unicode::Unihan
        use Unicode::Unihan;
        my $str = "XX";
        my $unhan = Unicode::Unihan->new;
        for my $lang (qw(Mandarin Cantonese Korean JapaneseOn JapaneseKun)) {
            printf "CJK $str in %-12s is ", $lang;
            say $unhan->$lang($str);


        CJK XX in Mandarin     is DONG1JING1
        CJK XX in Cantonese    is dung1ging1
        CJK XX in Korean       is TONGKYENG
        CJK XX in JapaneseOn   is TOUKYOU KEI KIN
        CJK XX in JapaneseKun  is HIGASHI AZUMAMIYAKO

       If you have a specific romanization scheme in mind, use the specific

        # cpan -i Lingua::JA::Romanize::Japanese
        use Lingua::JA::Romanize::Japanese;
        my $k2r = Lingua::JA::Romanize::Japanese->new;
        my $str = "XX";
        say "Japanese for $str is ", $k2r->chars($str);


        Japanese for XX is toukyou

   X 12: Explicit encode/decode
       On rare occasion, such as a database read, you may be given encoded
       text you need to decode.

         use Encode qw(encode decode);

         my $chars = decode("shiftjis", $bytes, 1);
        # OR
         my $bytes = encode("MIME-Header-ISO_2022_JP", $chars, 1);

       For streams all in the same encoding, don't use encode/decode; instead
       set the file encoding when you open the file or immediately after with
       "binmode" as described later below.

   X 13: Decode program arguments as utf8
            $ perl -CA ...
            $ export PERL_UNICODE=A
           use Encode qw(decode);
           @ARGV = map { decode('UTF-8', $_, 1) } @ARGV;

   X 14: Decode program arguments as locale encoding
           # cpan -i Encode::Locale
           use Encode qw(locale);
           use Encode::Locale;

           # use "locale" as an arg to encode/decode
           @ARGV = map { decode(locale => $_, 1) } @ARGV;

   X 15: Declare STD{IN,OUT,ERR} to be utf8
       Use a command-line option, an environment variable, or else call
       "binmode" explicitly:

            $ perl -CS ...
            $ export PERL_UNICODE=S
            use open qw(:std :encoding(UTF-8));
            binmode(STDIN,  ":encoding(UTF-8)");
            binmode(STDOUT, ":utf8");
            binmode(STDERR, ":utf8");

   X 16: Declare STD{IN,OUT,ERR} to be in locale encoding
           # cpan -i Encode::Locale
           use Encode;
           use Encode::Locale;

           # or as a stream for binmode or open
           binmode STDIN,  ":encoding(console_in)"  if -t STDIN;
           binmode STDOUT, ":encoding(console_out)" if -t STDOUT;
           binmode STDERR, ":encoding(console_out)" if -t STDERR;

   X 17: Make file I/O default to utf8
       Files opened without an encoding argument will be in UTF-8:

            $ perl -CD ...
            $ export PERL_UNICODE=D
            use open qw(:encoding(UTF-8));

   X 18: Make all I/O and args default to utf8
            $ perl -CSDA ...
            $ export PERL_UNICODE=SDA
            use open qw(:std :encoding(UTF-8));
            use Encode qw(decode);
            @ARGV = map { decode('UTF-8', $_, 1) } @ARGV;

   X 19: Open file with specific encoding
       Specify stream encoding.  This is the normal way to deal with encoded
       text, not by calling low-level functions.

        # input file
            open(my $in_file, "< :encoding(UTF-16)", "wintext");
            open(my $in_file, "<", "wintext");
            binmode($in_file, ":encoding(UTF-16)");
            my $line = <$in_file>;

        # output file
            open($out_file, "> :encoding(cp1252)", "wintext");
            open(my $out_file, ">", "wintext");
            binmode($out_file, ":encoding(cp1252)");
            print $out_file "some text\n";

       More layers than just the encoding can be specified here. For example,
       the incantation ":raw :encoding(UTF-16LE) :crlf" includes implicit CRLF

   X 20: Unicode casing
       Unicode casing is very different from ASCII casing.

        uc("henry X")  # "HENRY X"
        uc("tschuess")   # "TSCHUeSS"  notice ss => SS

        # both are true:
        "tschuess"  =~ /TSCHUeSS/i   # notice ss => SS
        "XXXXXXX" =~ /XXXXXXX/i   # notice X,X,X sameness

   X 21: Unicode case-insensitive comparisons
       Also available in the CPAN Unicode::CaseFold module, the new "fc"
       XfoldcaseX function from v5.16 grants access to the same Unicode
       casefolding as the "/i" pattern modifier has always used:

        use feature "fc"; # fc() function is from v5.16

        # sort case-insensitively
        my @sorted = sort { fc($a) cmp fc($b) } @list;

        # both are true:
        fc("tschuess")  eq fc("TSCHUeSS")
        fc("XXXXXXX") eq fc("XXXXXXX")

   X 22: Match Unicode linebreak sequence in regex
       A Unicode linebreak matches the two-character CRLF grapheme or any of
       seven vertical whitespace characters.  Good for dealing with textfiles
       coming from different operating systems.


        s/\R/\n/g;  # normalize all linebreaks to \n

   X 23: Get character category
       Find the general category of a numeric codepoint.

        use Unicode::UCD qw(charinfo);
        my $cat = charinfo(0x3A3)->{category};  # "Lu"

   X 24: Disabling Unicode-awareness in builtin charclasses
       Disable "\w", "\b", "\s", "\d", and the POSIX classes from working
       correctly on Unicode either in this scope, or in just one regex.

        use v5.14;
        use re "/a";

        # OR

        my($num) = $str =~ /(\d+)/a;

       Or use specific un-Unicode properties, like "\p{ahex}" and
       "\p{POSIX_Digit"}.  Properties still work normally no matter what
       charset modifiers ("/d /u /l /a /aa") should be effect.

   X 25: Match Unicode properties in regex with \p, \P
       These all match a single codepoint with the given property.  Use "\P"
       in place of "\p" to match one codepoint lacking that property.

        \pL, \pN, \pS, \pP, \pM, \pZ, \pC
        \p{Sk}, \p{Ps}, \p{Lt}
        \p{alpha}, \p{upper}, \p{lower}
        \p{Latin}, \p{Greek}
        \p{script_extensions=Latin}, \p{scx=Greek}
        \p{East_Asian_Width=Wide}, \p{EA=W}
        \p{Line_Break=Hyphen}, \p{LB=HY}
        \p{Numeric_Value=4}, \p{NV=4}

   X 26: Custom character properties
       Define at compile-time your own custom character properties for use in

        # using private-use characters
        sub In_Tengwar { "E000\tE07F\n" }

        if (/\p{In_Tengwar}/) { ... }

        # blending existing properties
        sub Is_GraecoRoman_Title {<<'END_OF_SET'}

        if (/\p{Is_GraecoRoman_Title}/ { ... }

   X 27: Unicode normalization
       Typically render into NFD on input and NFC on output. Using NFKC or
       NFKD functions improves recall on searches, assuming you've already
       done to the same text to be searched. Note that this is about much more
       than just pre- combined compatibility glyphs; it also reorders marks
       according to their canonical combining classes and weeds out

        use Unicode::Normalize;
        my $nfd  = NFD($orig);
        my $nfc  = NFC($orig);
        my $nfkd = NFKD($orig);
        my $nfkc = NFKC($orig);

   X 28: Convert non-ASCII Unicode numerics
       Unless youXve used "/a" or "/aa", "\d" matches more than ASCII digits
       only, but PerlXs implicit string-to-number conversion does not current
       recognize these.  HereXs how to convert such strings manually.

        use v5.14;  # needed for num() function
        use Unicode::UCD qw(num);
        my $str = "got X and XXXX and X and here";
        my @nums = ();
        while ($str =~ /(\d+|\N)/g) {  # not just ASCII!
           push @nums, num($1);
        say "@nums";   #     12      4567      0.875

        use charnames qw(:full);
        my $nv = num("\N{RUMI DIGIT ONE}\N{RUMI DIGIT TWO}");

   X 29: Match Unicode grapheme cluster in regex
       Programmer-visible XcharactersX are codepoints matched by "/./s", but
       user-visible XcharactersX are graphemes matched by "/\X/".

        # Find vowel *plus* any combining diacritics,underlining,etc.
        my $nfd = NFD($orig);
        $nfd =~ / (?=[aeiou]) \X /xi

   X 30: Extract by grapheme instead of by codepoint (regex)
        # match and grab five first graphemes
        my($first_five) = $str =~ /^ ( \X{5} ) /x;

   X 31: Extract by grapheme instead of by codepoint (substr)
        # cpan -i Unicode::GCString
        use Unicode::GCString;
        my $gcs = Unicode::GCString->new($str);
        my $first_five = $gcs->substr(0, 5);

   X 32: Reverse string by grapheme
       Reversing by codepoint messes up diacritics, mistakenly converting
       "creme brulee" into "eelXurb emXerc" instead of into "eelurb emerc"; so
       reverse by grapheme instead.  Both these approaches work right no
       matter what normalization the string is in:

        $str = join("", reverse $str =~ /\X/g);

        # OR: cpan -i Unicode::GCString
        use Unicode::GCString;
        $str = reverse Unicode::GCString->new($str);

   X 33: String length in graphemes
       The string "brulee" has six graphemes but up to eight codepoints.  This
       counts by grapheme, not by codepoint:

        my $str = "brulee";
        my $count = 0;
        while ($str =~ /\X/g) { $count++ }

         # OR: cpan -i Unicode::GCString
        use Unicode::GCString;
        my $gcs = Unicode::GCString->new($str);
        my $count = $gcs->length;

   X 34: Unicode column-width for printing
       PerlXs "printf", "sprintf", and "format" think all codepoints take up 1
       print column, but many take 0 or 2.  Here to show that normalization
       makes no difference, we print out both forms:

        use Unicode::GCString;
        use Unicode::Normalize;

        my @words = qw/creme brulee/;
        @words = map { NFC($_), NFD($_) } @words;

        for my $str (@words) {
            my $gcs = Unicode::GCString->new($str);
            my $cols = $gcs->columns;
            my $pad = " " x (10 - $cols);
            say str, $pad, " |";

       generates this to show that it pads correctly no matter the

        creme      |
        creXme      |
        brulee     |
        bruXleXe     |

   X 35: Unicode collation
       Text sorted by numeric codepoint follows no reasonable alphabetic
       order; use the UCA for sorting text.

        use Unicode::Collate;
        my $col = Unicode::Collate->new();
        my @list = $col->sort(@old_list);

       See the ucsort program from the Unicode::Tussle CPAN module for a
       convenient command-line interface to this module.

   X 36: Case- and accent-insensitive Unicode sort
       Specify a collation strength of level 1 to ignore case and diacritics,
       only looking at the basic character.

        use Unicode::Collate;
        my $col = Unicode::Collate->new(level => 1);
        my @list = $col->sort(@old_list);

   X 37: Unicode locale collation
       Some locales have special sorting rules.

        # either use v5.12, OR: cpan -i Unicode::Collate::Locale
        use Unicode::Collate::Locale;
        my $col = Unicode::Collate::Locale->new(locale => "de__phonebook");
        my @list = $col->sort(@old_list);

       The ucsort program mentioned above accepts a "--locale" parameter.

   X 38: Making "cmp" work on text instead of codepoints
       Instead of this:

        @srecs = sort {
            $b->{AGE}   <=>  $a->{AGE}
            $a->{NAME}  cmp  $b->{NAME}
        } @recs;

       Use this:

        my $coll = Unicode::Collate->new();
        for my $rec (@recs) {
            $rec->{NAME_key} = $coll->getSortKey( $rec->{NAME} );
        @srecs = sort {
            $b->{AGE}       <=>  $a->{AGE}
            $a->{NAME_key}  cmp  $b->{NAME_key}
        } @recs;

   X 39: Case- and accent-insensitive comparisons
       Use a collator object to compare Unicode text by character instead of
       by codepoint.

        use Unicode::Collate;
        my $es = Unicode::Collate->new(
            level => 1,
            normalization => undef

         # now both are true:
        $es->eq("Garcia",  "GARCIA" );
        $es->eq("Marquez", "MARQUEZ");

   X 40: Case- and accent-insensitive locale comparisons
       Same, but in a specific locale.

        my $de = Unicode::Collate::Locale->new(
                   locale => "de__phonebook",

        # now this is true:
        $de->eq("tschuess", "TSCHUESS");  # notice ue => UE, ss => SS

   X 41: Unicode linebreaking
       Break up text into lines according to Unicode rules.

        # cpan -i Unicode::LineBreak
        use Unicode::LineBreak;
        use charnames qw(:full);

        my $para = "This is a super\N{HYPHEN}long string. " x 20;
        my $fmt = Unicode::LineBreak->new;
        print $fmt->break($para), "\n";

   X 42: Unicode text in DBM hashes, the tedious way
       Using a regular Perl string as a key or value for a DBM hash will
       trigger a wide character exception if any codepoints wonXt fit into a
       byte.  HereXs how to manually manage the translation:

           use DB_File;
           use Encode qw(encode decode);
           tie %dbhash, "DB_File", "pathname";

        # STORE

           # assume $uni_key and $uni_value are abstract Unicode strings
           my $enc_key   = encode("UTF-8", $uni_key, 1);
           my $enc_value = encode("UTF-8", $uni_value, 1);
           $dbhash{$enc_key} = $enc_value;

        # FETCH

           # assume $uni_key holds a normal Perl string (abstract Unicode)
           my $enc_key   = encode("UTF-8", $uni_key, 1);
           my $enc_value = $dbhash{$enc_key};
           my $uni_value = decode("UTF-8", $enc_value, 1);

   X 43: Unicode text in DBM hashes, the easy way
       HereXs how to implicitly manage the translation; all encoding and
       decoding is done automatically, just as with streams that have a
       particular encoding attached to them:

           use DB_File;
           use DBM_Filter;

           my $dbobj = tie %dbhash, "DB_File", "pathname";
           $dbobj->Filter_Value("utf8");  # this is the magic bit

        # STORE

           # assume $uni_key and $uni_value are abstract Unicode strings
           $dbhash{$uni_key} = $uni_value;

         # FETCH

           # $uni_key holds a normal Perl string (abstract Unicode)
           my $uni_value = $dbhash{$uni_key};

   X 44: PROGRAM: Demo of Unicode collation and printing
       HereXs a full program showing how to make use of locale-sensitive
       sorting, Unicode casing, and managing print widths when some of the
       characters take up zero or two columns, not just one column each time.
       When run, the following program produces this nicely aligned output:

           Creme Brulee....... X2.00
           Eclair............. X1.60
           Fideua............. X4.20
           Hamburger.......... X6.00
           Jamon Serrano...... X4.45
           Linguica........... X7.00
           Pate............... X4.15
           Pears.............. X2.00
           Peches............. X2.25
           Smorbrod........... X5.75
           Spaetzle............ X5.50
           Xorico............. X3.00
           XXXXX.............. X6.50
           XXX............. X4.00
           XXX............. X2.65
           XXXXX......... X8.00
           XXXXXXX..... X1.85
           XX............... X9.99
           XX............... X7.50

       Here's that program; tested on v5.14.

        #!/usr/bin/env perl
        # umenu - demo sorting and printing of Unicode food
        # (obligatory and increasingly long preamble)
        use utf8;
        use v5.14;                       # for locale sorting
        use strict;
        use warnings;
        use warnings  qw(FATAL utf8);    # fatalize encoding faults
        use open      qw(:std :encoding(UTF-8)); # undeclared streams in UTF-8
        use charnames qw(:full :short);  # unneeded in v5.16

        # std modules
        use Unicode::Normalize;          # std perl distro as of v5.8
        use List::Util qw(max);          # std perl distro as of v5.10
        use Unicode::Collate::Locale;    # std perl distro as of v5.14

        # cpan modules
        use Unicode::GCString;           # from CPAN

        # forward defs
        sub pad($$$);
        sub colwidth(_);
        sub entitle(_);

        my %price = (
            "XXXXX"             => 6.50, # gyros
            "pears"             => 2.00, # like um, pears
            "linguica"          => 7.00, # spicy sausage, Portuguese
            "xorico"            => 3.00, # chorizo sausage, Catalan
            "hamburger"         => 6.00, # burgermeister meisterburger
            "eclair"            => 1.60, # dessert, French
            "smorbrod"          => 5.75, # sandwiches, Norwegian
            "spaetzle"           => 5.50, # Bayerisch noodles, little sparrows
            "XX"              => 7.50, # bao1 zi5, steamed pork buns, Mandarin
            "jamon serrano"     => 4.45, # country ham, Spanish
            "peches"            => 2.25, # peaches, French
            "XXXXXXX"    => 1.85, # cream-filled pastry like eclair
            "XXX"            => 4.00, # makgeolli, Korean rice wine
            "XX"              => 9.99, # sushi, Japanese
            "XXX"            => 2.65, # omochi, rice cakes, Japanese
            "creme brulee"      => 2.00, # crema catalana
            "fideua"            => 4.20, # more noodles, Valencian
                                         # (Catalan=fideuada)
            "pate"              => 4.15, # gooseliver paste, French
            "XXXXX"        => 8.00, # okonomiyaki, Japanese

        my $width = 5 + max map { colwidth } keys %price;

        # So the Asian stuff comes out in an order that someone
        # who reads those scripts won't freak out over; the
        # CJK stuff will be in JIS X 0208 order that way.
        my $coll  = Unicode::Collate::Locale->new(locale => "ja");

        for my $item ($coll->sort(keys %price)) {
            print pad(entitle($item), $width, ".");
            printf " X%.2f\n", $price{$item};

        sub pad($$$) {
            my($str, $width, $padchar) = @_;
            return $str . ($padchar x ($width - colwidth($str)));

        sub colwidth(_) {
            my($str) = @_;
            return Unicode::GCString->new($str)->columns;

        sub entitle(_) {
            my($str) = @_;
            $str =~ s{ (?=\pL)(\S)     (\S*) }
                     { ucfirst($1) . lc($2)  }xge;
            return $str;


       See these manpages, some of which are CPAN modules: perlunicode(1),
       perluniprops(1), perlre(1), perlrecharclass(1), perluniintro(1),
       perlunitut(1), perlunifaq(1), PerlIO(3), DB_File(3), DBM_Filter(3),
       DBM_Filter::utf8(3), Encode(3), Encode::Locale(3), Unicode::UCD(3),
       Unicode::Normalize(3), Unicode::GCString(3), Unicode::LineBreak(3),
       Unicode::Collate(3), Unicode::Collate::Locale(3),
       Unicode::Unihan(3), Unicode::CaseFold(3), Unicode::Tussle(3),
       Lingua::JA::Romanize::Japanese(3), Lingua::ZH::Romanize::Pinyin(3),

       The Unicode::Tussle(3) CPAN module includes many programs to help with
       working with Unicode, including these programs to fully or partly
       replace standard utilities: tcgrep instead of egrep, uniquote instead
       of cat -v or hexdump, uniwc instead of wc, unilook instead of look,
       unifmt instead of fmt, and ucsort instead of sort.  For exploring
       Unicode character names and character properties, see its uniprops,
       unichars, and uninames programs.  It also supplies these programs, all
       of which are general filters that do Unicode-y things: unititle and
       unicaps; uniwide and uninarrow; unisupers and unisubs; nfd, nfc, nfkd,
       and nfkc; and uc, lc, and tc.

       Finally, see the published Unicode Standard (page numbers are from
       version 6.0.0), including these specific annexes and technical reports:

       X3.13 Default Case Algorithms, page 113; X4.2  Case, pages 120X122;
       Case Mappings, page 166X172, especially Caseless Matching starting on
       page 170.
       UAX #44: Unicode Character Database
       UTS #18: Unicode Regular Expressions
       UAX #15: Unicode Normalization Forms
       UTS #10: Unicode Collation Algorithm
       UAX #29: Unicode Text Segmentation
       UAX #14: Unicode Line Breaking Algorithm
       UAX #11: East Asian Width


       Tom Christiansen <> wrote this, with occasional
       kibbitzing from Larry Wall and Jeffrey Friedl in the background.


       Copyright X 2012 Tom Christiansen.

       This program is free software; you may redistribute it and/or modify it
       under the same terms as Perl itself.

       Most of these examples taken from the current edition of the XCamel
       BookX; that is, from the 4XX Edition of Programming Perl, Copyright X
       2012 Tom Christiansen <et al.>, 2012-02-13 by OXReilly Media.  The code
       itself is freely redistributable, and you are encouraged to transplant,
       fold, spindle, and mutilate any of the examples in this manpage however
       you please for inclusion into your own programs without any encumbrance
       whatsoever.  Acknowledgement via code comment is polite but not


       v1.0.0 X first public release, 2012-02-27

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