WCTOMB
Section: POSIX Programmer's Manual (3P)
Updated: 2017
Page Index
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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.1-2017 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 .