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' (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 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 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'\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.

ATTRIBUTES

   Multithreading (see pthreads(7))
       The  mbrtowc()  function  is thread-safe with exceptions.  It is not thread-safe if called with a NULL ps
       parameter.

CONFORMING TO

       C99.

NOTES

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

SEE ALSO

       mbsrtowcs(3)

COLOPHON

       This page is part of release 3.54 of the Linux man-pages project.  A  description  of  the  project,  and
       information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.

GNU                                                2013-06-21                                         MBRTOWC(3)