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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
       The functionality described on this reference page is aligned with  the
       ISO C  standard.  Any  conflict between the requirements described here
       and the ISO C standard is unintentional. This  volume  of  POSIX.1-2008
       defers to the ISO C standard.
       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 POSIX.1-2008
       calls mbrtowc().
       The behavior of this function is affected by the LC_CTYPE  category  of
       the current locale.
       The mbrtowc() function need not be thread-safe if called with a NULL ps
       argument.
       The mbrtowc() function shall not change the setting of  errno  if  suc-
       cessful.
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
                   corresponds  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  poten-
                   tially 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  implementa-
                   tions 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 char-
                   acter (no value is stored). In this case, [EILSEQ] shall be
                   stored in errno and the conversion state is undefined.
ERRORS
       The mbrtowc() function shall fail if:
       EILSEQ An invalid character sequence is detected.
       The mbrtowc() function may fail if:
       EINVAL ps points to an  object  that  contains  an  invalid  conversion
              state.
       The following sections are informative.
EXAMPLES
       None.
APPLICATION USAGE
       None.
RATIONALE
       None.
FUTURE DIRECTIONS
       None.
SEE ALSO
       mbsinit(), mbsrtowcs()
       The Base Definitions volume of POSIX.1-2008, <wchar.h>
COPYRIGHT
       Portions  of  this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri-
       cal  and  Electronics  Engineers,  Inc  and  The  Open Group.  (This is
       POSIX.1-2008 with the 2013 Technical Corrigendum  1  applied.)  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.unix.org/online.html .
       Any typographical or formatting errors that appear  in  this  page  are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors,  see  https://www.ker-
       nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group                  2013                          MBRTOWC(3P)