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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
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.1‐2008 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.1‐2008 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.1‐2008, <stdlib.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition,
Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers, Inc
and The Open Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/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 .