This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface

       None.

       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                                        WCTOMB(3POSIX)

       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.

       The wctomb() function shall determine the number of bytes needed to represent the character corresponding
       to the wide-character code whose value is wchar (including any change in the shift state). It shall store
       the character representation (possibly multiple bytes and any special bytes to change shift state) in the
       array object pointed to by s (if s is not a null pointer). At most {MB_CUR_MAX} bytes shall be stored. If
       wchar  is  0,  a  null byte shall be stored, preceded by any shift sequence needed to restore the initial
       shift state, and wctomb() shall be left in the initial shift state.

       The behavior of this function is affected by the LC_CTYPE category of the current locale.  For  a  state-
       dependent  encoding,  this  function  shall  be  placed  into  its  initial state by a call for which its
       character pointer argument, s, is a null pointer. Subsequent calls with s as other than  a  null  pointer
       shall  cause  the  internal  state  of  the  function to be altered as necessary. A call with s as a null
       pointer shall cause this function to return a non-zero value if encodings have state  dependency,  and  0
       otherwise. Changing the LC_CTYPE category causes the shift state of this function to be unspecified.

       The wctomb() function need not be thread-safe.

       The implementation shall behave as if no function defined in this volume of POSIX.1‐2017 calls wctomb().

       The wctomb() function shall fail if:

       EILSEQ An invalid wide-character code is detected.

       Thefollowingsectionsareinformative.

       None.

       None.

       wctomb — convert a wide-character code to a character

       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.

       None.

       If  s  is  a  null  pointer,  wctomb()  shall  return  a  non-zero  or  0  value, if character encodings,
       respectively, do or do not have state-dependent encodings. If s is not a  null  pointer,  wctomb()  shall
       return  -1  if the value of wchar does not correspond to a valid character, or return the number of bytes
       that constitute the character corresponding to the value of wchar.

       In no case shall the value returned be greater than the value of the {MB_CUR_MAX} macro.

mblen(), mbtowc(), mbstowcs(), wcstombs()

       The Base Definitions volume of POSIX.1‐2017, <stdlib.h>

       #include <stdlib.h>

       int wctomb(char *s, wchar_t wchar);