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 # Convert a code point from the platform native character set to
46 # Unicode, and vice-versa.
47 $unicode = utf8::native_to_unicode(ord('A')); # returns 65 on both
50 $native = utf8::unicode_to_native(65); # returns 65 on ASCII
51 # platforms; 193 on EBCDIC
53 $flag = utf8::is_utf8($string); # since Perl 5.8.1
54 $flag = utf8::valid($string);
58 The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the
59 program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based
60 platforms). The C<no utf8> pragma tells Perl to switch back to treating
61 the source text as literal bytes in the current lexical scope.
63 B<Do not use this pragma for anything else than telling Perl that your
64 script is written in UTF-8.> The utility functions described below are
65 directly usable without C<use utf8;>.
67 Because it is not possible to reliably tell UTF-8 from native 8 bit
68 encodings, you need either a Byte Order Mark at the beginning of your
69 source code, or C<use utf8;>, to instruct perl.
71 When UTF-8 becomes the standard source format, this pragma will
72 effectively become a no-op. For convenience in what follows the term
73 I<UTF-X> is used to refer to UTF-8 on ASCII and ISO Latin based
74 platforms and UTF-EBCDIC on EBCDIC based platforms.
76 See also the effects of the C<-C> switch and its cousin, the
77 C<PERL_UNICODE> environment variable, in L<perlrun>.
79 Enabling the C<utf8> pragma has the following effect:
85 Bytes in the source text that have their high-bit set will be treated
86 as being part of a literal UTF-X sequence. This includes most
87 literals such as identifier names, string constants, and constant
88 regular expression patterns.
90 On EBCDIC platforms characters in the Latin 1 character set are
91 treated as being part of a literal UTF-EBCDIC character.
95 Note that if you have bytes with the eighth bit on in your script
96 (for example embedded Latin-1 in your string literals), C<use utf8>
97 will be unhappy since the bytes are most probably not well-formed
98 UTF-X. If you want to have such bytes under C<use utf8>, you can disable
99 this pragma until the end the block (or file, if at top level) by
102 =head2 Utility functions
104 The following functions are defined in the C<utf8::> package by the
105 Perl core. You do not need to say C<use utf8> to use these and in fact
106 you should not say that unless you really want to have UTF-8 source code.
110 =item * C<$num_octets = utf8::upgrade($string)>
112 Converts in-place the internal representation of the string from an octet
113 sequence in the native encoding (Latin-1 or EBCDIC) to I<UTF-X>. The
114 logical character sequence itself is unchanged. If I<$string> is already
115 stored as I<UTF-X>, then this is a no-op. Returns the
116 number of octets necessary to represent the string as I<UTF-X>. Can be
117 used to make sure that the UTF-8 flag is on, so that C<\w> or C<lc()>
118 work as Unicode on strings containing characters in the range 0x80-0xFF
119 (on ASCII and derivatives).
121 B<Note that this function does not handle arbitrary encodings.>
122 Therefore Encode is recommended for the general purposes; see also
125 =item * C<$success = utf8::downgrade($string[, $fail_ok])>
127 Converts in-place the internal representation of the string from
128 I<UTF-X> to the equivalent octet sequence in the native encoding (Latin-1
129 or EBCDIC). The logical character sequence itself is unchanged. If
130 I<$string> is already stored as native 8 bit, then this is a no-op. Can
132 make sure that the UTF-8 flag is off, e.g. when you want to make sure
133 that the substr() or length() function works with the usually faster
136 Fails if the original I<UTF-X> sequence cannot be represented in the
137 native 8 bit encoding. On failure dies or, if the value of I<$fail_ok> is
140 Returns true on success.
142 B<Note that this function does not handle arbitrary encodings.>
143 Therefore Encode is recommended for the general purposes; see also
146 =item * C<utf8::encode($string)>
148 Converts in-place the character sequence to the corresponding octet
149 sequence in I<UTF-X>. That is, every (possibly wide) character gets
150 replaced with a sequence of one or more characters that represent the
151 individual I<UTF-X> bytes of the character. The UTF8 flag is turned off.
154 my $a = "\x{100}"; # $a contains one character, with ord 0x100
155 utf8::encode($a); # $a contains two characters, with ords (on
156 # ASCII platforms) 0xc4 and 0x80
158 B<Note that this function does not handle arbitrary encodings.>
159 Therefore Encode is recommended for the general purposes; see also
162 =item * C<$success = utf8::decode($string)>
164 Attempts to convert in-place the octet sequence encoded as I<UTF-X> to the
165 corresponding character sequence. That is, it replaces each sequence of
166 characters in the string whose ords represent a valid UTF-X byte
167 sequence, with the corresponding single character. The UTF-8 flag is
168 turned on only if the source string contains multiple-byte I<UTF-X>
169 characters. If I<$string> is invalid as I<UTF-X>, returns false;
170 otherwise returns true.
172 my $a = "\xc4\x80"; # $a contains two characters, with ords
174 utf8::decode($a); # On ASCII platforms, $a contains one char,
175 # with ord 0x100. On EBCDIC platforms, $a
176 # is unchanged and the function returns FALSE.
178 (C<"\xc4\x80"> is not a valid sequence of bytes in any UTF-8-encoded
179 character(s) in the EBCDIC code pages that Perl supports, which is why the
180 above example returns failure on them. What does decode into C<\x{100}>
181 depends on the platform. It is C<"\x8C\x41"> in IBM-1047.)
183 B<Note that this function does not handle arbitrary encodings.>
184 Therefore Encode is recommended for the general purposes; see also
187 =item * C<$unicode = utf8::native_to_unicode($code_point)>
190 This takes an unsigned integer (which represents the ordinal number of a
191 character (or a code point) on the platform the program is being run on) and
192 returns its Unicode equivalent value. Since ASCII platforms natively use the
193 Unicode code points, this function returns its input on them. On EBCDIC
194 platforms it converts from EBCDIC to Unicode.
196 A meaningless value will currently be returned if the input is not an unsigned
199 Since Perl v5.22.0, calls to this function are optimized out on ASCII
200 platforms, so there is no performance hit in using it there.
202 =item * C<$native = utf8::unicode_to_native($code_point)>
205 This is the inverse of C<utf8::native_to_unicode()>, converting the other
206 direction. Again, on ASCII platforms, this returns its input, but on EBCDIC
207 platforms it will find the native platform code point, given any Unicode one.
209 A meaningless value will currently be returned if the input is not an unsigned
212 Since Perl v5.22.0, calls to this function are optimized out on ASCII
213 platforms, so there is no performance hit in using it there.
215 =item * C<$flag = utf8::is_utf8($string)>
217 (Since Perl 5.8.1) Test whether I<$string> is marked internally as encoded in
218 UTF-8. Functionally the same as Encode::is_utf8().
220 =item * C<$flag = utf8::valid($string)>
222 [INTERNAL] Test whether I<$string> is in a consistent state regarding
223 UTF-8. Will return true if it is well-formed UTF-8 and has the UTF-8 flag
224 on B<or> if I<$string> is held as bytes (both these states are 'consistent').
225 Main reason for this routine is to allow Perl's test suite to check
226 that operations have left strings in a consistent state. You most
227 probably want to use utf8::is_utf8() instead.
231 C<utf8::encode> is like C<utf8::upgrade>, but the UTF8 flag is
232 cleared. See L<perlunicode> for more on the UTF8 flag and the C API
233 functions C<sv_utf8_upgrade>, C<sv_utf8_downgrade>, C<sv_utf8_encode>,
234 and C<sv_utf8_decode>, which are wrapped by the Perl functions
235 C<utf8::upgrade>, C<utf8::downgrade>, C<utf8::encode> and
236 C<utf8::decode>. Also, the functions utf8::is_utf8, utf8::valid,
237 utf8::encode, utf8::decode, utf8::upgrade, and utf8::downgrade are
238 actually internal, and thus always available, without a C<require utf8>
243 One can have Unicode in identifier names, but not in package/class or
244 subroutine names. While some limited functionality towards this does
245 exist as of Perl 5.8.0, that is more accidental than designed; use of
246 Unicode for the said purposes is unsupported.
248 One reason of this unfinishedness is its (currently) inherent
249 unportability: since both package names and subroutine names may need
250 to be mapped to file and directory names, the Unicode capability of
251 the filesystem becomes important-- and there unfortunately aren't
256 L<perlunitut>, L<perluniintro>, L<perlrun>, L<bytes>, L<perlunicode>