WCRTOMB(3)                 POSIX Programmer's Manual                WCRTOMB(3)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

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.1-2017
       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.1-2017 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.1-2017, <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                           WCRTOMB(3)
