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                                      WCSTOMBS(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  wcstombs() function shall convert the sequence of wide-character codes that are in the array pointed
       to by pwcs into a sequence of characters  that  begins  in  the  initial  shift  state  and  store  these
       characters  into  the  array  pointed  to by s, stopping if a character would exceed the limit of n total
       bytes or if a null byte is stored. Each wide-character code shall  be  converted  as  if  by  a  call  to
       wctomb(), except that the shift state of wctomb() shall not be affected.

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

       No  more  than  n  bytes  shall be modified in the array pointed to by s.  If copying takes place between
       objects that overlap, the behavior is undefined.  If s is a null pointer,  wcstombs()  shall  return  the
       length required to convert the entire array regardless of the value of n, but no values are stored.

       The wcstombs() function shall fail if:

       EILSEQ A wide-character code does not correspond to a valid character.

       Thefollowingsectionsareinformative.

       None.

       None.

       wcstombs — convert a wide-character string to a character string

       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  a  wide-character  code  is encountered that does not correspond to a valid character (of one or more
       bytes each), wcstombs() shall return (size_t)-1. Otherwise, wcstombs() shall return the number  of  bytes
       stored  in  the  character  array,  not including any terminating null byte. The array shall not be null-
       terminated if the value returned is n.

mblen(), mbtowc(), mbstowcs(), wctomb()

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

       #include <stdlib.h>

       size_t wcstombs(char *restrict s, const wchar_t *restrict pwcs,
           size_t n);