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



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.


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, """",, 11,, 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
       character 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
       conversion 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
       successful.

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
                   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]
                   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
       Electrical 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.kernel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group                  2013                           MBRTOWC(3)
