WCTOMB(3)                  POSIX Programmer's Manual                 WCTOMB(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
       wctomb -- convert a wide-character code to a character

SYNOPSIS
       #include <stdlib.h>

       int wctomb(char *_s, wchar_t wchar);

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.

       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().

RETURN VALUE
       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.

ERRORS
       The wctomb() function shall fail if:

       EILSEQ An invalid wide-character code is detected.

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       mblen(), mbtowc(), mbstowcs(), wcstombs()

       The Base Definitions volume of POSIX.1-2017, <stdlib.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                            WCTOMB(3)
