3 $utf8::hint_bits = 0x00800000;
8 $^H |= $utf8::hint_bits;
9 $enc{caller()} = $_[1] if $_[1];
13 $^H &= ~$utf8::hint_bits;
17 require "utf8_heavy.pl";
18 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
36 The C<use utf8> pragma tells the Perl parser to allow UTF-8 in the
37 program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based
38 platforms). The C<no utf8> pragma tells Perl to switch back to treating
39 the source text as literal bytes in the current lexical scope.
41 This pragma is primarily a compatibility device. Perl versions
42 earlier than 5.6 allowed arbitrary bytes in source code, whereas
43 in future we would like to standardize on the UTF-8 encoding for
44 source text. Until UTF-8 becomes the default format for source
45 text, this pragma should be used to recognize UTF-8 in the source.
46 When UTF-8 becomes the standard source format, this pragma will
47 effectively become a no-op. For convenience in what follows the
48 term I<UTF-X> is used to refer to UTF-8 on ASCII and ISO Latin based
49 platforms and UTF-EBCDIC on EBCDIC based platforms.
51 Enabling the C<utf8> pragma has the following effect:
57 Bytes in the source text that have their high-bit set will be treated
58 as being part of a literal UTF-8 character. This includes most
59 literals such as identifiers, string constants, constant regular
60 expression patterns and package names. On EBCDIC platforms characters
61 in the Latin 1 character set are treated as being part of a literal
66 Note that if you have bytes with the eighth bit on in your script
67 (for example embedded Latin-1 in your string literals), C<use utf8>
68 will be unhappy since the bytes are most probably not well-formed
69 UTF-8. If you want to have such bytes and use utf8, you can disable
70 utf8 until the end the block (or file, if at top level) by C<no utf8;>.
72 =head2 Utility functions
74 The following functions are defined in the C<utf8::> package by the perl core.
78 =item * $num_octets = utf8::upgrade($string);
80 Converts internal representation of string to the Perl's internal
81 I<UTF-X> form. Returns the number of octets necessary to represent
82 the string as I<UTF-X>. Note that this should not be used to convert
83 a legacy byte encoding to Unicode: use Encode for that. Affected
84 by the encoding pragma.
86 =item * utf8::downgrade($string[, CHECK])
88 Converts internal representation of string to be un-encoded bytes.
89 Note that this should not be used to convert Unicode back to a legacy
90 byte encoding: use Encode for that. B<Not> affected by the encoding
93 =item * utf8::encode($string)
95 Converts (in-place) I<$string> from logical characters to octet
96 sequence representing it in Perl's I<UTF-X> encoding. Note that this
97 should not be used to convert a legacy byte encoding to Unicode: use
100 =item * $flag = utf8::decode($string)
102 Attempts to convert I<$string> in-place from Perl's I<UTF-X> encoding
103 into logical characters. Note that this should not be used to convert
104 Unicode back to a legacy byte encoding: use Encode for that.
106 =item * $flag = utf8::valid(STRING)
108 [INTERNAL] Test whether STRING is in a consistent state. Will return
109 true if string is held as bytes, or is well-formed UTF-8 and has the
110 UTF-8 flag on. Main reason for this routine is to allow Perl's
111 testsuite to check that operations have left strings in a consistent
116 C<utf8::encode> is like C<utf8::upgrade>, but the UTF8 flag is cleared.
117 See L<perlunicode> for more on the UTF8 flag and the C API functions
118 C<sv_utf8_upgrade>, C<sv_utf8_downgrade>, C<sv_utf8_encode>,
119 and C<sv_utf8_decode>, which are wrapped by the Perl functions
120 C<utf8::upgrade>, C<utf8::downgrade>, C<utf8::encode> and
125 L<perlunicode>, L<bytes>