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

       wcsnrtombs, wcsrtombs — convert a wide-character string to a character string (restartable)

SYNOPSIS

       #include <wchar.h>

       size_t wcsnrtombs(char *restrict dst, const wchar_t **restrict src,
           size_t nwc, size_t len, mbstate_t *restrict ps);
       size_t wcsrtombs(char *restrict dst, const wchar_t **restrict src,
           size_t len, mbstate_t *restrict ps);

DESCRIPTION

       For  wcsrtombs():  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 wcsrtombs() function shall convert a sequence of wide characters from the array indirectly pointed to
       by src into a sequence of corresponding characters, beginning in the conversion state  described  by  the
       object  pointed  to  by  ps.  If dst is not a null pointer, the converted characters shall then be stored
       into the array pointed to by dst.  Conversion continues up to  and  including  a  terminating  null  wide
       character, which shall also be stored. Conversion shall stop earlier in the following cases:

        *  When a code is reached that does not correspond to a valid character

        *  When  the  next character would exceed the limit of len total bytes to be stored in the array pointed
           to by dst (and dst is not a null pointer)

       Each conversion shall take place as if by a call to the wcrtomb() function.

       If dst is not a null pointer, the pointer object pointed to by  src  shall  be  assigned  either  a  null
       pointer  (if  conversion  stopped  due to reaching a terminating null wide character) or the address just
       past the last wide character converted (if any). If conversion stopped due to reaching a terminating null
       wide character, the resulting state described shall be the initial conversion state.

       If ps is a null pointer, the wcsrtombs() 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 wcsnrtombs() and wcsrtombs() functions need not be thread-safe if called with a NULL ps argument.

       The  wcsnrtombs() function shall be equivalent to the wcsrtombs() function, except that the conversion is
       limited to the first nwc wide characters.

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

       The behavior of these functions shall be affected by the LC_CTYPE category of the current locale.

       The implementation shall behave as if no function defined in System  Interfaces  volume  of  POSIX.1‐2017
       calls these functions.

RETURN VALUE

       If  conversion stops because a code is reached that does not correspond to a valid character, an encoding
       error occurs. In this case, these functions shall store the value of the  macro  [EILSEQ]  in  errno  and
       return (size_t)-1; the conversion state is undefined.  Otherwise, these functions shall return the number
       of bytes in the resulting character sequence, not including the terminating null (if any).

ERRORS

       These functions shall fail if:

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

       These functions 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(), wcrtomb()

       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                                     WCSRTOMBS(3POSIX)