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
54 $flag = utf8::is_utf8($string); # since Perl 5.8.1
55 $flag = utf8::valid($string);
59 The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the
60 program text in the current lexical scope. The C<no utf8> pragma tells Perl
61 to switch back to treating the source text as literal bytes in the current
62 lexical scope. (On EBCDIC platforms, technically it is allowing UTF-EBCDIC,
63 and not UTF-8, but this distinction is academic, so in this document the term
64 UTF-8 is used to mean both).
66 B<Do not use this pragma for anything else than telling Perl that your
67 script is written in UTF-8.> The utility functions described below are
68 directly usable without C<use utf8;>.
70 Because it is not possible to reliably tell UTF-8 from native 8 bit
71 encodings, you need either a Byte Order Mark at the beginning of your
72 source code, or C<use utf8;>, to instruct perl.
74 When UTF-8 becomes the standard source format, this pragma will
75 effectively become a no-op.
77 See also the effects of the C<-C> switch and its cousin, the
78 C<PERL_UNICODE> environment variable, in L<perlrun>.
80 Enabling the C<utf8> pragma has the following effect:
86 Bytes in the source text that are not in the ASCII character set will be
87 treated as being part of a literal UTF-8 sequence. This includes most
88 literals such as identifier names, string constants, and constant
89 regular expression patterns.
93 Note that if you have non-ASCII, non-UTF-8 bytes in your script (for example
94 embedded Latin-1 in your string literals), C<use utf8> will be unhappy. If
95 you want to have such bytes under C<use utf8>, you can disable this pragma
96 until the end the block (or file, if at top level) by C<no utf8;>.
98 =head2 Utility functions
100 The following functions are defined in the C<utf8::> package by the
101 Perl core. You do not need to say C<use utf8> to use these and in fact
102 you should not say that unless you really want to have UTF-8 source code.
106 =item * C<$num_octets = utf8::upgrade($string)>
109 Converts in-place the internal representation of the string from an octet
110 sequence in the native encoding (Latin-1 or EBCDIC) to UTF-8. The
111 logical character sequence itself is unchanged. If I<$string> is already
112 stored as UTF-8, then this is a no-op. Returns the
113 number of octets necessary to represent the string as UTF-8. Can be
114 used to make sure that the UTF-8 flag is on, so that C<\w> or C<lc()>
115 work as Unicode on strings containing non-ASCII characters whose code points
118 B<Note that this function does not handle arbitrary encodings>;
119 use L<Encode> instead.
121 =item * C<$success = utf8::downgrade($string[, $fail_ok])>
124 Converts in-place the internal representation of the string from
125 UTF-8 to the equivalent octet sequence in the native encoding (Latin-1
126 or EBCDIC). The logical character sequence itself is unchanged. If
127 I<$string> is already stored as native 8 bit, then this is a no-op. Can
129 make sure that the UTF-8 flag is off, e.g. when you want to make sure
130 that the substr() or length() function works with the usually faster
133 Fails if the original UTF-8 sequence cannot be represented in the
134 native 8 bit encoding. On failure dies or, if the value of I<$fail_ok> is
137 Returns true on success.
139 B<Note that this function does not handle arbitrary encodings>;
140 use L<Encode> instead.
142 =item * C<utf8::encode($string)>
145 Converts in-place the character sequence to the corresponding octet
146 sequence in UTF-8. That is, every (possibly wide) character gets
147 replaced with a sequence of one or more characters that represent the
148 individual UTF-8 bytes of the character. The UTF8 flag is turned off.
151 my $a = "\x{100}"; # $a contains one character, with ord 0x100
152 utf8::encode($a); # $a contains two characters, with ords (on
153 # ASCII platforms) 0xc4 and 0x80. On EBCDIC
154 # 1047, this would instead be 0x8C and 0x41.
156 B<Note that this function does not handle arbitrary encodings>;
157 use L<Encode> instead.
159 =item * C<$success = utf8::decode($string)>
162 Attempts to convert in-place the octet sequence encoded as UTF-8 to the
163 corresponding character sequence. That is, it replaces each sequence of
164 characters in the string whose ords represent a valid UTF-8 byte
165 sequence, with the corresponding single character. The UTF-8 flag is
166 turned on only if the source string contains multiple-byte UTF-8
167 characters. If I<$string> is invalid as UTF-8, returns false;
168 otherwise returns true.
170 my $a = "\xc4\x80"; # $a contains two characters, with ords
172 utf8::decode($a); # On ASCII platforms, $a contains one char,
173 # with ord 0x100. Since these bytes aren't
174 # legal UTF-EBCDIC, on EBCDIC platforms, $a is
175 # unchanged and the function returns FALSE.
177 B<Note that this function does not handle arbitrary encodings>;
178 use L<Encode> instead.
180 =item * C<$unicode = utf8::native_to_unicode($code_point)>
183 This takes an unsigned integer (which represents the ordinal number of a
184 character (or a code point) on the platform the program is being run on) and
185 returns its Unicode equivalent value. Since ASCII platforms natively use the
186 Unicode code points, this function returns its input on them. On EBCDIC
187 platforms it converts from EBCDIC to Unicode.
189 A meaningless value will currently be returned if the input is not an unsigned
192 Since Perl v5.22.0, calls to this function are optimized out on ASCII
193 platforms, so there is no performance hit in using it there.
195 =item * C<$native = utf8::unicode_to_native($code_point)>
198 This is the inverse of C<utf8::native_to_unicode()>, converting the other
199 direction. Again, on ASCII platforms, this returns its input, but on EBCDIC
200 platforms it will find the native platform code point, given any Unicode one.
202 A meaningless value will currently be returned if the input is not an unsigned
205 Since Perl v5.22.0, calls to this function are optimized out on ASCII
206 platforms, so there is no performance hit in using it there.
208 =item * C<$flag = utf8::is_utf8($string)>
210 (Since Perl 5.8.1) Test whether I<$string> is marked internally as encoded in
211 UTF-8. Functionally the same as C<Encode::is_utf8()>.
213 =item * C<$flag = utf8::valid($string)>
215 [INTERNAL] Test whether I<$string> is in a consistent state regarding
216 UTF-8. Will return true if it is well-formed UTF-8 and has the UTF-8 flag
217 on B<or> if I<$string> is held as bytes (both these states are 'consistent').
218 Main reason for this routine is to allow Perl's test suite to check
219 that operations have left strings in a consistent state. You most
220 probably want to use C<utf8::is_utf8()> instead.
224 C<utf8::encode> is like C<utf8::upgrade>, but the UTF8 flag is
225 cleared. See L<perlunicode>, and the C API
226 functions C<L<sv_utf8_upgrade|perlapi/sv_utf8_upgrade>>,
227 C<L<perlapi/sv_utf8_downgrade>>, C<L<perlapi/sv_utf8_encode>>,
228 and C<L<perlapi/sv_utf8_decode>>, which are wrapped by the Perl functions
229 C<utf8::upgrade>, C<utf8::downgrade>, C<utf8::encode> and
230 C<utf8::decode>. Also, the functions C<utf8::is_utf8>, C<utf8::valid>,
231 C<utf8::encode>, C<utf8::decode>, C<utf8::upgrade>, and C<utf8::downgrade> are
232 actually internal, and thus always available, without a C<require utf8>
237 Some filesystems may not support UTF-8 file names, or they may be supported
238 incompatibly with Perl. Therefore UTF-8 names that are visible to the
239 filesystem, such as module names may not work.
243 L<perlunitut>, L<perluniintro>, L<perlrun>, L<bytes>, L<perlunicode>