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MULTIBYTE(3)          DragonFly Library Functions Manual          MULTIBYTE(3)


NAME

     multibyte -- multibyte and wide character manipulation functions


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <limits.h>
     #include <stdlib.h>
     #include <wchar.h>


DESCRIPTION

     The basic elements of some written natural languages, such as Chinese,
     cannot be represented uniquely with single C chars.  The C standard
     supports two different ways of dealing with extended natural language
     encodings: wide characters and multibyte characters.  Wide characters are
     an internal representation which allows each basic element to map to a
     single object of type wchar_t.  Multibyte characters are used for input
     and output and code each basic element as a sequence of C chars.
     Individual basic elements may map into one or more (up to MB_LEN_MAX)
     bytes in a multibyte character.

     The current locale (setlocale(3)) governs the interpretation of wide and
     multibyte characters.  The locale category LC_CTYPE specifically controls
     this interpretation.  The wchar_t type is wide enough to hold the largest
     value in the wide character representations for all locales.

     Multibyte strings may contain `shift' indicators to switch to and from
     particular modes within the given representation.  If explicit bytes are
     used to signal shifting, these are not recognized as separate characters
     but are lumped with a neighboring character.  There is always a
     distinguished `initial' shift state.  Some functions (e.g., mblen(3),
     mbtowc(3) and wctomb(3)) maintain static shift state internally, whereas
     others store it in an mbstate_t object passed by the caller.  Shift
     states are undefined after a call to setlocale(3) with the LC_CTYPE or
     LC_ALL categories.

     For convenience in processing, the wide character with value 0 (the null
     wide character) is recognized as the wide character string terminator,
     and the character with value 0 (the null byte) is recognized as the
     multibyte character string terminator.  Null bytes are not permitted
     within multibyte characters.

     The C library provides the following functions for dealing with multibyte
     characters:

     Function       Description
     mblen(3)       get number of bytes in a character
     mbrlen(3)      get number of bytes in a character (restartable)
     mbrtowc(3)     convert a character to a wide-character code (restartable)
     mbsrtowcs(3)   convert a character string to a wide-character string
                    (restartable)
     mbstowcs(3)    convert a character string to a wide-character string
     mbtowc(3)      convert a character to a wide-character code
     mbintowcr(3)   convert bytes-to-wchars with escaping, and validation
     wcrtomb(3)     convert a wide-character code to a character (restartable)
     wcstombs(3)    convert a wide-character string to a character string
     wcsrtombs(3)   convert a wide-character string to a character string
                    (restartable)
     wctomb(3)      convert a wide-character code to a character
     wcrtombin(3)   convert wchars-to-bytes with descaping, and validation
     wcrtoutf8(3)   locale-independent UTF8-specific version of wcrtombin
     utf8towcr(3)   locale-independent UTF8-specific version of mbintowcr


SEE ALSO

     localedef(1), setlocale(3), stdio(3), big5(5), euc(5), gb18030(5),
     gb2312(5), gbk(5), mskanji(5), utf8(5)


STANDARDS

     These functions conform to ISO/IEC 9899:1999 (``ISO C99'').

DragonFly 4.3                    April 8, 2004                   DragonFly 4.3

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