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

       wcrtomb — convert a wide-character code to a character (restartable)

SYNOPSIS

       #include <wchar.h>

       size_t wcrtomb(char *restrict s, wchar_t wc, 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 wcrtomb() function shall be equivalent to the call:

           wcrtomb(buf, L'\0', ps)

       where buf is an internal buffer.

       If  s  is  not  a null pointer, the wcrtomb() function shall determine the number of bytes
       needed to represent the character that corresponds to  the  wide  character  given  by  wc
       (including  any  shift  sequences), and store the resulting bytes in the array whose first
       element is pointed to by s.  At most {MB_CUR_MAX} bytes are stored. If wc is a  null  wide
       character,  a  null byte shall be stored, preceded by any shift sequence needed to restore
       the initial shift state. The resulting state described shall  be  the  initial  conversion
       state.

       If  ps  is  a  null  pointer,  the wcrtomb() 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.1‐2008 calls wcrtomb().

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

       The  behavior  of  this function shall be affected by the LC_CTYPE category of the current
       locale.

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

RETURN VALUE

       The wcrtomb() function shall return the  number  of  bytes  stored  in  the  array  object
       (including  any shift sequences). When wc is not a valid wide character, an encoding error
       shall occur. In this case, the function shall store the value of  the  macro  [EILSEQ]  in
       errno and shall return (size_t)−1; the conversion state shall be undefined.

ERRORS

       The wcrtomb() function shall fail if:

       EILSEQ An invalid wide-character code is detected.

       The wcrtomb() 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(), wcsrtombs()

       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 .