GIF89a; EcchiShell v1.0
//proc/self/root/usr/share/perl5/

pragma tells the Perl parser to allow UTF-8 in the program text in the current lexical scope (allow UTF-EBCDIC on EBCDIC based platforms). The C pragma tells Perl to switch back to treating the source text as literal bytes in the current lexical scope. B The utility functions described below are directly usable without C. Because it is not possible to reliably tell UTF-8 from native 8 bit encodings, you need either a Byte Order Mark at the beginning of your source code, or C, to instruct perl. When UTF-8 becomes the standard source format, this pragma will effectively become a no-op. For convenience in what follows the term I is used to refer to UTF-8 on ASCII and ISO Latin based platforms and UTF-EBCDIC on EBCDIC based platforms. See also the effects of the C<-C> switch and its cousin, the C<$ENV{PERL_UNICODE}>, in L. Enabling the C pragma has the following effect: =over 4 =item * Bytes in the source text that have their high-bit set will be treated as being part of a literal UTF-X sequence. This includes most literals such as identifier names, string constants, and constant regular expression patterns. On EBCDIC platforms characters in the Latin 1 character set are treated as being part of a literal UTF-EBCDIC character. =back Note that if you have bytes with the eighth bit on in your script (for example embedded Latin-1 in your string literals), C will be unhappy since the bytes are most probably not well-formed UTF-X. If you want to have such bytes under C, you can disable this pragma until the end the block (or file, if at top level) by C. =head2 Utility functions The following functions are defined in the C package by the Perl core. You do not need to say C to use these and in fact you should not say that unless you really want to have UTF-8 source code. =over 4 =item * $num_octets = utf8::upgrade($string) Converts in-place the internal representation of the string from an octet sequence in the native encoding (Latin-1 or EBCDIC) to I. The logical character sequence itself is unchanged. If I<$string> is already stored as I, then this is a no-op. Returns the number of octets necessary to represent the string as I. Can be used to make sure that the UTF-8 flag is on, so that C<\w> or C work as Unicode on strings containing characters in the range 0x80-0xFF (on ASCII and derivatives). B Therefore Encode is recommended for the general purposes; see also L. =item * $success = utf8::downgrade($string[, FAIL_OK]) Converts in-place the internal representation of the string from I to the equivalent octet sequence in the native encoding (Latin-1 or EBCDIC). The logical character sequence itself is unchanged. If I<$string> is already stored as native 8 bit, then this is a no-op. Can be used to make sure that the UTF-8 flag is off, e.g. when you want to make sure that the substr() or length() function works with the usually faster byte algorithm. Fails if the original I sequence cannot be represented in the native 8 bit encoding. On failure dies or, if the value of C is true, returns false. Returns true on success. B Therefore Encode is recommended for the general purposes; see also L. =item * utf8::encode($string) Converts in-place the character sequence to the corresponding octet sequence in I. That is, every (possibly wide) character gets replaced with a sequence of one or more characters that represent the individual I bytes of the character. The UTF8 flag is turned off. Returns nothing. my $a = "\x{100}"; # $a contains one character, with ord 0x100 utf8::encode($a); # $a contains two characters, with ords 0xc4 and 0x80 B Therefore Encode is recommended for the general purposes; see also L. =item * $success = utf8::decode($string) Attempts to convert in-place the octet sequence in I to the corresponding character sequence. That is, it replaces each sequence of characters in the string whose ords represent a valid UTF-X byte sequence, with the corresponding single character. The UTF-8 flag is turned on only if the source string contains multiple-byte I characters. If I<$string> is invalid as I, returns false; otherwise returns true. my $a = "\xc4\x80"; # $a contains two characters, with ords 0xc4 and 0x80 utf8::decode($a); # $a contains one character, with ord 0x100 B Therefore Encode is recommended for the general purposes; see also L. =item * $flag = utf8::is_utf8(STRING) (Since Perl 5.8.1) Test whether STRING is in UTF-8 internally. Functionally the same as Encode::is_utf8(). =item * $flag = utf8::valid(STRING) [INTERNAL] Test whether STRING is in a consistent state regarding UTF-8. Will return true is well-formed UTF-8 and has the UTF-8 flag on B if string is held as bytes (both these states are 'consistent'). Main reason for this routine is to allow Perl's testsuite to check that operations have left strings in a consistent state. You most probably want to use utf8::is_utf8() instead. =back C is like C, but the UTF8 flag is cleared. See L for more on the UTF8 flag and the C API functions C, C, C, and C, which are wrapped by the Perl functions C, C, C and C. Also, the functions utf8::is_utf8, utf8::valid, utf8::encode, utf8::decode, utf8::upgrade, and utf8::downgrade are actually internal, and thus always available, without a C statement. =head1 BUGS One can have Unicode in identifier names, but not in package/class or subroutine names. While some limited functionality towards this does exist as of Perl 5.8.0, that is more accidental than designed; use of Unicode for the said purposes is unsupported. One reason of this unfinishedness is its (currently) inherent unportability: since both package names and subroutine names may need to be mapped to file and directory names, the Unicode capability of the filesystem becomes important-- and there unfortunately aren't portable answers. =head1 SEE ALSO L, L, L, L, L =cut