redhat 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'', 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, excepts 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. Oth-
       erwise, the mbrtowc function puts *ps in the initial state and returns 0.

       In  all	of  the above cases, if ps is a NULL pointer, a static anonymous state only known to the mbrtowc function is used instead.  Other-
       wise, *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 recog-
       nized.	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.

CONFORMING TO
       ISO/ANSI C, UNIX98

SEE ALSO
       mbsrtowcs(3)

NOTES
       The behaviour of mbrtowc depends on the LC_CTYPE category of the current locale.

GNU
								    2001-11-22								MBRTOWC(3)