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MULTIBYTE(3)		 BSD Library Functions Manual		  MULTIBYTE(3)

     mblen, mbstowcs, mbtowc, wcstombs,	wctomb -- multibyte character support
     for C

     Standard C	Library	(libc, -lc)

     #include <stdlib.h>

     mblen(const char *mbchar, size_t nbytes);

     mbstowcs(wchar_t *	restrict wcstring, const char *	restrict mbstring,
	 size_t	nwchars);

     mbtowc(wchar_t * restrict wcharp, const char * restrict mbchar,
	 size_t	nbytes);

     wcstombs(char * restrict mbstring,	const wchar_t *	restrict wcstring,
	 size_t	nbytes);

     wctomb(char *mbchar, wchar_t wchar);

     The basic elements	of some	written	natural	languages such as Chinese can-
     not 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 inter-
     nal representation	which allows each basic	element	to map to a single ob-
     ject 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

     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 distin-
     guished `initial' shift state.  The mbstowcs() and	wcstombs() functions
     assume that multibyte strings are interpreted starting from the initial
     shift state.  The mblen(),	mbtowc() and wctomb() functions	maintain
     static shift state	internally.  A call with a null	mbchar pointer returns
     nonzero if	the current locale requires shift states, zero otherwise; if
     shift states are required,	the shift state	is reset to the	initial	state.
     The internal shift	states are undefined after a call to setlocale() 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 mblen() function computes the length in bytes of a multibyte charac-
     ter mbchar.  Up to	nbytes bytes are examined.

     The mbtowc() function converts a multibyte	character mbchar into a	wide
     character and stores the result in	the object pointed to by wcharp.  Up
     to	nbytes bytes are examined.

     The wctomb() function converts a wide character wchar into	a multibyte
     character and stores the result in	mbchar.	 The object pointed to by
     mbchar must be large enough to accommodate	the multibyte character.

     The mbstowcs() function converts a	multibyte character string mbstring
     into a wide character string wcstring.  No	more than nwchars wide charac-
     ters are stored.  A terminating null wide character is appended if	there
     is	room.

     The wcstombs() function converts a	wide character string wcstring into a
     multibyte character string	mbstring.  Up to nbytes	bytes are stored in
     mbstring.	Partial	multibyte characters at	the end	of the string are not
     stored.  The multibyte character string is	null terminated	if there is

     If	mbchar is NULL,	the mblen(), mbtowc() and wctomb() functions return
     nonzero if	shift states are supported, zero otherwise.  If	mbchar is
     valid, then these functions return	the number of bytes processed in
     mbchar, or	-1 if no multibyte character could be recognized or converted.

     The mbstowcs() function returns the number	of wide	characters converted,
     not counting any terminating null wide character.	The wcstombs() func-
     tion returns the number of	bytes converted, not counting any terminating
     null byte.	 If any	invalid	multibyte characters are encountered, both
     functions return -1.

     btowc(3), mbrlen(3), mbrtowc(3), mbrune(3), mbsrtowcs(3), rune(3),
     setlocale(3), wcrtomb(3), wcsrtombs(3), euc(4), utf2(4), utf8(5)

     The mblen(), mbstowcs(), mbtowc(),	wcstombs() and wctomb()	functions con-
     form to ISO/IEC 9899:1990 ("ISO C90").

     The current implementation	does not support shift states.

BSD				October	6, 2002				   BSD


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