MBRLEN(3)                  POSIX Programmer's Manual                 MBRLEN(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
       mbrlen -- get number of bytes in a character (restartable)

SYNOPSIS
       #include <wchar.h>

       size_t mbrlen(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.1-2017
       defers to the ISO C standard.

       If _s is not a null pointer, mbrlen() shall determine the number of
       bytes constituting the character pointed to by _s.  It shall be
       equivalent to:


           mbstate_t internal;
           mbrtowc(NULL, s, n, ps != NULL ? ps : &internal);

       If ps is a null pointer, the mbrlen() function shall use its own
       internal mbstate_t object, which is 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.1-2017 calls
       mbrlen().

       The behavior of this function is affected by the LC__CTYPE category of
       the current locale.

       The mbrlen() function need not be thread-safe if called with a NULL ps
       argument.

       The mbrlen() function shall not change the setting of errno if
       successful.

RETURN VALUE
       The mbrlen() 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.

       positive    If the next _n or fewer bytes complete a valid character;
                   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. 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. In this case, [EILSEQ] shall be stored in errno
                   and the conversion state is undefined.

ERRORS
       The mbrlen() function shall fail if:

       EILSEQ An invalid character sequence is detected.  In the POSIX locale
              an [EILSEQ] error cannot occur since all byte values are valid
              characters.

       The mbrlen() 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(), mbrtowc()

       The Base Definitions volume of POSIX.1-2017, <wchar.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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 .

       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                  2017                            MBRLEN(3)
