x11r4 man page for mbrtowc

MBRTOWC(3)						     Linux Programmer's Manual							MBRTOWC(3)

NAME
       mbrtowc - convert a multibyte sequence to a wide character

SYNOPSIS
       #include <wchar.h>

       size_t mbrtowc(wchar_t *pwc, const char *s, size_t n, mbstate_t *ps);

DESCRIPTION
       The  main  case for this function is when s is not NULL and pwc is not NULL.  In this case, the mbrtowc() function inspects at most n bytes
       of the multibyte string starting at s, extracts the next complete multibyte character, converts it to a wide character  and  stores  it	at
       *pwc.   It  updates  the shift state *ps.  If the converted wide character is not L'' (the null wide character), it returns the number of
       bytes that were consumed from s.  If the converted wide character is L'', it resets the shift state *ps to the initial state and  returns
       0.

       If  the	n  bytes starting at s do not contain a complete multibyte character, mbrtowc() returns (size_t) -2.  This can happen even if n >=
       MB_CUR_MAX, if the multibyte string contains redundant shift sequences.

       If the multibyte string starting at s contains an invalid  multibyte  sequence  before  the  next  complete  character,	mbrtowc()  returns
       (size_t) -1 and sets errno to EILSEQ.  In this case, the effects on *ps are undefined.

       A  different  case  is  when s is not NULL but pwc is NULL.  In this case, the mbrtowc() function behaves as above, except that it does not
       store the converted wide character in memory.

       A third case is when s is NULL.	In this case, pwc and n are ignored.  If the conversion state represented by  *ps  denotes  an	incomplete
       multibyte  character  conversion,  the  mbrtowc() function returns (size_t) -1, sets errno to EILSEQ, and leaves *ps in an undefined state.
       Otherwise, the mbrtowc() function puts *ps in the initial state and returns 0.

       In all of the above cases, if ps is NULL, a static anonymous state known only to the mbrtowc() function is used	instead.   Otherwise,  *ps
       must be a valid mbstate_t object.  An mbstate_t object a can be initialized to the initial state by zeroing it, for example using

	   memset(&a, 0, sizeof(a));

RETURN VALUE
       The mbrtowc() function returns the number of bytes parsed from the multibyte sequence starting at s, if a non-L'' wide character was rec-
       ognized.  It returns 0, if a L'' wide character was recognized.  It returns (size_t) -1 and sets errno to EILSEQ, if an invalid multibyte
       sequence was encountered.  It returns (size_t) -2 if it couldn't parse a complete multibyte character, meaning that n should be increased.

ATTRIBUTES
       For an explanation of the terms used in this section, see attributes(7).

       +----------+---------------+----------------------------+
       |Interface | Attribute	  | Value		       |
       +----------+---------------+----------------------------+
       |mbrtowc() | Thread safety | MT-Unsafe race:mbrtowc/!ps |
       +----------+---------------+----------------------------+
CONFORMING TO
       POSIX.1-2001, POSIX.1-2008, C99.

NOTES
       The behavior of mbrtowc() depends on the LC_CTYPE category of the current locale.

SEE ALSO
       mbsinit(3), mbsrtowcs(3)

COLOPHON
       This  page is part of release 4.15 of the Linux man-pages project.  A description of the project, information about reporting bugs, and the
       latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

GNU
								    2015-08-08								MBRTOWC(3)