mbrtowc


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 multi-
       byte 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'\0' (the null wide character), it returns the number  of  bytes  that
       were  consumed  from  s.   If the converted wide character is L'\0', 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  char-
       acter,  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 multi-
       byte  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 a NULL pointer, a static anonymous
       state only known 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'\0' wide character was
       recognized.  It returns 0, if a L'\0' wide  character  was  recognized.
       It  returns  (size_t) -1 and sets errno to EILSEQ, if an invalid multi-
       byte 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
       C99.



GNU                               2011-09-28                        MBRTOWC(3)
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