3 $utf8::hint_bits = 0x00800000;
8 $^H |= $utf8::hint_bits;
12 $^H &= ~$utf8::hint_bits;
16 require "utf8_heavy.pl";
17 goto &$AUTOLOAD if defined &$AUTOLOAD;
19 Carp::croak("Undefined subroutine $AUTOLOAD called");
27 utf8 - Perl pragma to enable/disable UTF-8 (or UTF-EBCDIC) in source code
34 # Convert the internal representation of a Perl scalar to/from UTF-8.
36 $num_octets = utf8::upgrade($string);
37 $success = utf8::downgrade($string[, FAIL_OK]);
39 # Change each character of a Perl scalar to/from a series of
40 # characters that represent the UTF-8 bytes of each original character.
42 utf8::encode($string); # "\x{100}" becomes "\xc4\x80"
43 utf8::decode($string); # "\xc4\x80" becomes "\x{100}"
45 $flag = utf8::is_utf8(STRING); # since Perl 5.8.1
46 $flag = utf8::valid(STRING);
50 The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the
51 program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based
52 platforms). The C<no utf8> pragma tells Perl to switch back to treating
53 the source text as literal bytes in the current lexical scope.
55 B<Do not use this pragma for anything else than telling Perl that your
56 script is written in UTF-8.> The utility functions described below are
57 directly usable without C<use utf8;>.
59 Because it is not possible to reliably tell UTF-8 from native 8 bit
60 encodings, you need either a Byte Order Mark at the beginning of your
61 source code, or C<use utf8;>, to instruct perl.
63 When UTF-8 becomes the standard source format, this pragma will
64 effectively become a no-op. For convenience in what follows the term
65 I<UTF-X> is used to refer to UTF-8 on ASCII and ISO Latin based
66 platforms and UTF-EBCDIC on EBCDIC based platforms.
68 See also the effects of the C<-C> switch and its cousin, the
69 C<$ENV{PERL_UNICODE}>, in L<perlrun>.
71 Enabling the C<utf8> pragma has the following effect:
77 Bytes in the source text that have their high-bit set will be treated
78 as being part of a literal UTF-X sequence. This includes most
79 literals such as identifier names, string constants, and constant
80 regular expression patterns.
82 On EBCDIC platforms characters in the Latin 1 character set are
83 treated as being part of a literal UTF-EBCDIC character.
87 Note that if you have bytes with the eighth bit on in your script
88 (for example embedded Latin-1 in your string literals), C<use utf8>
89 will be unhappy since the bytes are most probably not well-formed
90 UTF-X. If you want to have such bytes under C<use utf8>, you can disable
91 this pragma until the end the block (or file, if at top level) by
94 =head2 Utility functions
96 The following functions are defined in the C<utf8::> package by the
97 Perl core. You do not need to say C<use utf8> to use these and in fact
98 you should not say that unless you really want to have UTF-8 source code.
102 =item * $num_octets = utf8::upgrade($string)
104 Converts in-place the internal representation of the string from an octet
105 sequence in the native encoding (Latin-1 or EBCDIC) to I<UTF-X>. The
106 logical character sequence itself is unchanged. If I<$string> is already
107 stored as I<UTF-X>, then this is a no-op. Returns the
108 number of octets necessary to represent the string as I<UTF-X>. Can be
109 used to make sure that the UTF-8 flag is on, so that C<\w> or C<lc()>
110 work as Unicode on strings containing characters in the range 0x80-0xFF
111 (on ASCII and derivatives).
113 B<Note that this function does not handle arbitrary encodings.>
114 Therefore Encode is recommended for the general purposes; see also
117 =item * $success = utf8::downgrade($string[, FAIL_OK])
119 Converts in-place the internal representation of the string from
120 I<UTF-X> to the equivalent octet sequence in the native encoding (Latin-1
121 or EBCDIC). The logical character sequence itself is unchanged. If
122 I<$string> is already stored as native 8 bit, then this is a no-op. Can
124 make sure that the UTF-8 flag is off, e.g. when you want to make sure
125 that the substr() or length() function works with the usually faster
128 Fails if the original I<UTF-X> sequence cannot be represented in the
129 native 8 bit encoding. On failure dies or, if the value of C<FAIL_OK> is
132 Returns true on success.
134 B<Note that this function does not handle arbitrary encodings.>
135 Therefore Encode is recommended for the general purposes; see also
138 =item * utf8::encode($string)
140 Converts in-place the character sequence to the corresponding octet
141 sequence in I<UTF-X>. That is, every (possibly wide) character gets
142 replaced with a sequence of one or more characters that represent the
143 individual I<UTF-X> bytes of the character. The UTF8 flag is turned off.
146 my $a = "\x{100}"; # $a contains one character, with ord 0x100
147 utf8::encode($a); # $a contains two characters, with ords 0xc4 and
150 B<Note that this function does not handle arbitrary encodings.>
151 Therefore Encode is recommended for the general purposes; see also
154 =item * $success = utf8::decode($string)
156 Attempts to convert in-place the octet sequence in I<UTF-X> to the
157 corresponding character sequence. That is, it replaces each sequence of
158 characters in the string whose ords represent a valid UTF-X byte
159 sequence, with the corresponding single character. The UTF-8 flag is
160 turned on only if the source string contains multiple-byte I<UTF-X>
161 characters. If I<$string> is invalid as I<UTF-X>, returns false;
162 otherwise returns true.
164 my $a = "\xc4\x80"; # $a contains two characters, with ords
166 utf8::decode($a); # $a contains one character, with ord 0x100
168 B<Note that this function does not handle arbitrary encodings.>
169 Therefore Encode is recommended for the general purposes; see also
172 =item * $flag = utf8::is_utf8(STRING)
174 (Since Perl 5.8.1) Test whether STRING is marked internally as encoded in
175 UTF-8. Functionally the same as Encode::is_utf8().
177 =item * $flag = utf8::valid(STRING)
179 [INTERNAL] Test whether STRING is in a consistent state regarding
180 UTF-8. Will return true if it is well-formed UTF-8 and has the UTF-8 flag
181 on B<or> if STRING is held as bytes (both these states are 'consistent').
182 Main reason for this routine is to allow Perl's test suite to check
183 that operations have left strings in a consistent state. You most
184 probably want to use utf8::is_utf8() instead.
188 C<utf8::encode> is like C<utf8::upgrade>, but the UTF8 flag is
189 cleared. See L<perlunicode> for more on the UTF8 flag and the C API
190 functions C<sv_utf8_upgrade>, C<sv_utf8_downgrade>, C<sv_utf8_encode>,
191 and C<sv_utf8_decode>, which are wrapped by the Perl functions
192 C<utf8::upgrade>, C<utf8::downgrade>, C<utf8::encode> and
193 C<utf8::decode>. Also, the functions utf8::is_utf8, utf8::valid,
194 utf8::encode, utf8::decode, utf8::upgrade, and utf8::downgrade are
195 actually internal, and thus always available, without a C<require utf8>
200 One can have Unicode in identifier names, but not in package/class or
201 subroutine names. While some limited functionality towards this does
202 exist as of Perl 5.8.0, that is more accidental than designed; use of
203 Unicode for the said purposes is unsupported.
205 One reason of this unfinishedness is its (currently) inherent
206 unportability: since both package names and subroutine names may need
207 to be mapped to file and directory names, the Unicode capability of
208 the filesystem becomes important-- and there unfortunately aren't
213 L<perlunitut>, L<perluniintro>, L<perlrun>, L<bytes>, L<perlunicode>