mbrtowc(3C)

NAME

     mbrtowc - convert a character to a wide-character code (res-
     tartable)

SYNOPSIS

     #include <wchar.h>

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

DESCRIPTION

     If s is a null pointer, the mbrtowc() function is equivalent
     to the call:

     mbrtowc(NULL, ``'', 1, ps)

     In this case, the values of the  arguments  pwc  and  n  are
     ignored.

     If s is not a null pointer, the mbrtowc() function  inspects
     at  most  n  bytes beginning at the byte pointed to by  s to
     determine the number of bytes needed to  complete  the  next
     character  (including any shift sequences).  If the function
     determines that the next character is completed,  it  deter-
     mines  the  value  of  the  corresponding wide-character and
     then, if pwc is not a null pointer, stores that value in the
     object  pointed  to  by  pwc.  If  the  corresponding  wide-
     character is the null wide-character,  the  resulting  state
     described is the initial conversion state.

     If ps is a null pointer, the mbrtowc() function uses its own
     internal  mbstate_t  object, which is initialized at program
     startup to the initial conversion  state.    Otherwise,  the
     mbstate_t  object  pointed  to  by  ps is used to completely
     describe the current  conversion  state  of  the  associated
     character  sequence.  Solaris  will behave as if no function
     defined in the Solaris Reference Manual calls mbrtowc().

     The behavior of this function is affected  by  the  LC_CTYPE
     category of the current locale.  See environ(5).

RETURN VALUES

     The mbrtowc() function returns the first  of  the  following
     that applies:

     0     If the next n or fewer bytes  complete  the  character
           that  corresponds to the null wide-character (which is
           the value stored).

     positive
           If the next n or fewer bytes complete a valid  charac-
           ter (which is the value stored); the value returned is
           the number of bytes that complete the character.

     (size_t)-2
           If the next n bytes contribute to  an  incomplete  but
           potentially  valid   character,  and  all n bytes have
           been processed (no value is stored).   When n  has  at
           least the value of the MB_CUR_MAX macro, this case can
           only occur if  s points at  a  sequence  of  redundant
           shift   sequences  (for  implementations  with  state-
           dependent encodings).

     (size_t)-1
           If an encoding error occurs, in which case the next  n
           or  fewer  bytes  do  not contribute to a complete and
           valid  character (no value is stored).  In this  case,
           EILSEQ  is stored in errno and the conversion state is
           undefined.

ERRORS

     The mbrtowc() function may fail if:

     EINVAL
           The ps argument points to an object that  contains  an
           invalid conversion state.

     EILSEQ
           Invalid character sequence is detected.

ATTRIBUTES

     See attributes(5) for descriptions of the  following  attri-
     butes:

     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | MT-Level                    | See NOTES below             |
    |_____________________________|_____________________________|

SEE ALSO

     mbsinit(3C), setlocale(3C), attributes(5), environ(5)

NOTES

     If ps is not a null pointer, mbrtowc()  uses  the  mbstate_t
     object  pointed to by ps and the function can be used safely
     in multithreaded applications, as long as  setlocale(3C)  is
     not  being  called  to  change  the  locale. If ps is a null
     pointer, mbrtowc() uses its internal  mbstate_t  object  and
     the function is Unsafe in multithreaded applications.