multibyte(3)

NAME

multibyte - multibyte and wide character manipulation func

tions

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 char

acters 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 specifi

cally 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 ex

plicit bytes are
used to signal shifting, these are not recognized as sepa

rate characters
but are lumped with a neighboring character. There is al

ways 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-charac

ter string

(restartable)

mbstowcs(3) convert a character string to a wide-charac

ter string
mbtowc(3) convert a character to a wide-character code
wcrtomb(3) convert a wide-character code to a character

(restartable)
wcstombs(3) convert a wide-character string to a charac

ter string
wcsrtombs(3) convert a wide-character string to a charac

ter string

(restartable)

wctomb(3) convert a wide-character code to a character

SEE ALSO

mklocale(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'').

BSD April 8, 2004

BSD