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MBRTOWC(3P)                POSIX Programmer's Manual               MBRTOWC(3P)

PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the  corresponding
       Linux  manual page for details of Linux behavior), or the interface may
       not be implemented on Linux.
NAME
       mbrtowc - convert a character to a wide-character code (restartable)
SYNOPSIS
       #include <wchar.h>
       size_t mbrtowc(wchar_t *restrict pwc, const char *restrict s,
              size_t n, mbstate_t *restrict ps);

DESCRIPTION
       If s is a null pointer, the mbrtowc() function shall be  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 shall inspect 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 shall determine the value of the corresponding wide char-
       acter and then, if pwc is not a null pointer, shall store that value in
       the  object  pointed  to by pwc. If the corresponding wide character is
       the null wide character, the resulting state  described  shall  be  the
       initial conversion state.
       If  ps  is  a  null  pointer,  the mbrtowc() function shall use its own
       internal mbstate_t object, which shall be initialized at program start-
       up  to  the  initial  conversion state. Otherwise, the mbstate_t object
       pointed to by ps shall be used to completely describe the current  con-
       version  state of the associated character sequence. The implementation
       shall  behave  as  if  no  function   defined   in   this   volume   of
       IEEE Std 1003.1-2001 calls mbrtowc().
       The  behavior  of this function is affected by the LC_CTYPE category of
       the current locale.
RETURN VALUE
       The mbrtowc() function shall return the first  of  the  following  that
       applies:
       0      If  the next n or fewer bytes complete the character that corre-
              sponds to the null wide character (which is the value stored).
       between 1 and n inclusive
              If the next n or fewer bytes complete a valid  character  (which
              is  the value stored); the value returned shall be 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-depen-
              dent 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] shall be stored in
              errno and the conversion state is undefined.

ERRORS
       The mbrtowc() function may fail if:
       EINVAL ps points to an  object  that  contains  an  invalid  conversion
              state.
       EILSEQ Invalid character sequence is detected.

       The following sections are informative.
EXAMPLES
       None.
APPLICATION USAGE
       None.
RATIONALE
       None.
FUTURE DIRECTIONS
       None.
SEE ALSO
       mbsinit(),   the   Base  Definitions  volume  of  IEEE Std 1003.1-2001,
       <wchar.h>
COPYRIGHT
       Portions of this text are reprinted and reproduced in  electronic  form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
       event of any discrepancy between this version and the original IEEE and
       The Open Group Standard, the original IEEE and The Open Group  Standard
       is  the  referee document. The original Standard can be obtained online
       at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group                  2003                          MBRTOWC(3P)