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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’\0’, 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
       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 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
       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

       C99

NOTES

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

SEE ALSO

       mbsrtowcs(3)

COLOPHON

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