3 $utf8::hint_bits = 0x00800000;
8 $^H |= $utf8::hint_bits;
12 $^H &= ~$utf8::hint_bits;
16 goto &$AUTOLOAD if defined &$AUTOLOAD;
18 Carp::croak("Undefined subroutine $AUTOLOAD called");
26 utf8 - Perl pragma to enable/disable UTF-8 (or UTF-EBCDIC) in source code
33 # Convert the internal representation of a Perl scalar to/from UTF-8.
35 $num_octets = utf8::upgrade($string);
36 $success = utf8::downgrade($string[, $fail_ok]);
38 # Change each character of a Perl scalar to/from a series of
39 # characters that represent the UTF-8 bytes of each original character.
41 utf8::encode($string); # "\x{100}" becomes "\xc4\x80"
42 utf8::decode($string); # "\xc4\x80" becomes "\x{100}"
44 # Convert a code point from the platform native character set to
45 # Unicode, and vice-versa.
46 $unicode = utf8::native_to_unicode(ord('A')); # returns 65 on both
49 $native = utf8::unicode_to_native(65); # returns 65 on ASCII
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. The C<no utf8> pragma tells Perl
60 to switch back to treating the source text as literal bytes in the current
61 lexical scope. (On EBCDIC platforms, technically it is allowing UTF-EBCDIC,
62 and not UTF-8, but this distinction is academic, so in this document the term
63 UTF-8 is used to mean both).
65 B<Do not use this pragma for anything else than telling Perl that your
66 script is written in UTF-8.> The utility functions described below are
67 directly usable without C<use utf8;>.
69 Because it is not possible to reliably tell UTF-8 from native 8 bit
70 encodings, you need either a Byte Order Mark at the beginning of your
71 source code, or C<use utf8;>, to instruct perl.
73 When UTF-8 becomes the standard source format, this pragma will
74 effectively become a no-op.
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 are not in the ASCII character set will be
86 treated as being part of a literal UTF-8 sequence. This includes most
87 literals such as identifier names, string constants, and constant
88 regular expression patterns.
92 Note that if you have non-ASCII, non-UTF-8 bytes in your script (for example
93 embedded Latin-1 in your string literals), C<use utf8> will be unhappy. If
94 you want to have such bytes under C<use utf8>, you can disable this pragma
95 until the end the block (or file, if at top level) by C<no utf8;>.
97 =head2 Utility functions
99 The following functions are defined in the C<utf8::> package by the
100 Perl core. You do not need to say C<use utf8> to use these and in fact
101 you should not say that unless you really want to have UTF-8 source code.
105 =item * C<$num_octets = utf8::upgrade($string)>
108 Converts in-place the internal representation of the string from an octet
109 sequence in the native encoding (Latin-1 or EBCDIC) to UTF-8. The
110 logical character sequence itself is unchanged. If I<$string> is already
111 upgraded, then this is a no-op. Returns the
112 number of octets necessary to represent the string as UTF-8.
114 If your code needs to be compatible with versions of perl without
115 C<use feature 'unicode_strings';>, you can force Unicode semantics on
118 # force unicode semantics for $string without the
119 # "unicode_strings" feature
120 utf8::upgrade($string);
124 # without explicit or implicit use feature 'unicode_strings'
125 my $x = "\xDF"; # LATIN SMALL LETTER SHARP S
126 $x =~ /ss/i; # won't match
127 my $y = uc($x); # won't convert
129 $x =~ /ss/i; # matches
130 my $z = uc($x); # converts to "SS"
132 B<Note that this function does not handle arbitrary encodings>;
133 use L<Encode> instead.
135 =item * C<$success = utf8::downgrade($string[, $fail_ok])>
138 Converts in-place the internal representation of the string from UTF-8 to the
139 equivalent octet sequence in the native encoding (Latin-1 or EBCDIC). The
140 logical character sequence itself is unchanged. If I<$string> is already
141 stored as native 8 bit, then this is a no-op. Can be used to make sure that
142 the UTF-8 flag is off, e.g. when you want to make sure that the substr() or
143 length() function works with the usually faster byte algorithm.
145 Fails if the original UTF-8 sequence cannot be represented in the
146 native 8 bit encoding. On failure dies or, if the value of I<$fail_ok> is
149 Returns true on success.
151 If your code expects an octet sequence this can be used to validate
152 that you've received one:
154 # throw an exception if not representable as octets
155 utf8::downgrade($string)
157 # or do your own error handling
158 utf8::downgrade($string, 1) or die "string must be octets";
160 B<Note that this function does not handle arbitrary encodings>;
161 use L<Encode> instead.
163 =item * C<utf8::encode($string)>
166 Converts in-place the character sequence to the corresponding octet
167 sequence in Perl's extended UTF-8. That is, every (possibly wide) character
168 gets replaced with a sequence of one or more characters that represent the
169 individual UTF-8 bytes of the character. The UTF8 flag is turned off.
172 my $x = "\x{100}"; # $x contains one character, with ord 0x100
173 utf8::encode($x); # $x contains two characters, with ords (on
174 # ASCII platforms) 0xc4 and 0x80. On EBCDIC
175 # 1047, this would instead be 0x8C and 0x41.
180 $x = Encode::encode("utf8", $x);
182 B<Note that this function does not handle arbitrary encodings>;
183 use L<Encode> instead.
185 =item * C<$success = utf8::decode($string)>
188 Attempts to convert in-place the octet sequence encoded in Perl's extended
189 UTF-8 to the corresponding character sequence. That is, it replaces each
190 sequence of characters in the string whose ords represent a valid (extended)
191 UTF-8 byte sequence, with the corresponding single character. The UTF-8 flag
192 is turned on only if the source string contains multiple-byte UTF-8
193 characters. If I<$string> is invalid as extended UTF-8, returns false;
194 otherwise returns true.
196 my $x = "\xc4\x80"; # $x contains two characters, with ords
198 utf8::decode($x); # On ASCII platforms, $x contains one char,
199 # with ord 0x100. Since these bytes aren't
200 # legal UTF-EBCDIC, on EBCDIC platforms, $x is
201 # unchanged and the function returns FALSE.
203 B<Note that this function does not handle arbitrary encodings>;
204 use L<Encode> instead.
206 =item * C<$unicode = utf8::native_to_unicode($code_point)>
209 This takes an unsigned integer (which represents the ordinal number of a
210 character (or a code point) on the platform the program is being run on) and
211 returns its Unicode equivalent value. Since ASCII platforms natively use the
212 Unicode code points, this function returns its input on them. On EBCDIC
213 platforms it converts from EBCDIC to Unicode.
215 A meaningless value will currently be returned if the input is not an unsigned
218 Since Perl v5.22.0, calls to this function are optimized out on ASCII
219 platforms, so there is no performance hit in using it there.
221 =item * C<$native = utf8::unicode_to_native($code_point)>
224 This is the inverse of C<utf8::native_to_unicode()>, converting the other
225 direction. Again, on ASCII platforms, this returns its input, but on EBCDIC
226 platforms it will find the native platform code point, given any Unicode one.
228 A meaningless value will currently be returned if the input is not an unsigned
231 Since Perl v5.22.0, calls to this function are optimized out on ASCII
232 platforms, so there is no performance hit in using it there.
234 =item * C<$flag = utf8::is_utf8($string)>
236 (Since Perl 5.8.1) Test whether I<$string> is marked internally as encoded in
237 UTF-8. Functionally the same as C<Encode::is_utf8($string)>.
239 Typically only necessary for debugging and testing, if you need to
240 dump the internals of an SV, L<Devel::Peek's|Devel::Peek> Dump()
241 provides more detail in a compact form.
243 If you still think you need this outside of debugging, testing or
244 dealing with filenames, you should probably read L<perlunitut> and
245 L<perlunifaq/What is "the UTF8 flag"?>.
247 Don't use this flag as a marker to distinguish character and binary
248 data: that should be decided for each variable when you write your
251 To force unicode semantics in code portable to perl 5.8 and 5.10, call
252 C<utf8::upgrade($string)> unconditionally.
254 =item * C<$flag = utf8::valid($string)>
256 [INTERNAL] Test whether I<$string> is in a consistent state regarding
257 UTF-8. Will return true if it is well-formed Perl extended UTF-8 and has the
259 on B<or> if I<$string> is held as bytes (both these states are 'consistent').
260 The main reason for this routine is to allow Perl's test suite to check
261 that operations have left strings in a consistent state.
265 C<utf8::encode> is like C<utf8::upgrade>, but the UTF8 flag is
266 cleared. See L<perlunicode>, and the C API
267 functions C<L<sv_utf8_upgrade|perlapi/sv_utf8_upgrade>>,
268 C<L<perlapi/sv_utf8_downgrade>>, C<L<perlapi/sv_utf8_encode>>,
269 and C<L<perlapi/sv_utf8_decode>>, which are wrapped by the Perl functions
270 C<utf8::upgrade>, C<utf8::downgrade>, C<utf8::encode> and
271 C<utf8::decode>. Also, the functions C<utf8::is_utf8>, C<utf8::valid>,
272 C<utf8::encode>, C<utf8::decode>, C<utf8::upgrade>, and C<utf8::downgrade> are
273 actually internal, and thus always available, without a C<require utf8>
278 Some filesystems may not support UTF-8 file names, or they may be supported
279 incompatibly with Perl. Therefore UTF-8 names that are visible to the
280 filesystem, such as module names may not work.
284 L<perlunitut>, L<perluniintro>, L<perlrun>, L<bytes>, L<perlunicode>