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

       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 .