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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.1‐2008 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.1‐2008 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.1‐2008, <wchar.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 .