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MBRTOWC(3P) POSIX Programmer's Manual MBRTOWC(3P)
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.
mbrtowc — convert a character to a wide-character code (restartable)
#include <wchar.h>
size_t mbrtowc(wchar_t *restrict pwc, const char *restrict s,
size_t n, mbstate_t *restrict ps);
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 mbrtowc() function shall be equivalent to
the call:
mbrtowc(NULL, "", 1, ps)
In this case, the values of the arguments pwc and n are ignored.
If s is not a null pointer, the mbrtowc() function shall inspect at
most n bytes beginning at the byte pointed to by s to determine the
number of bytes needed to complete the next character (including any
shift sequences). If the function determines that the next character
is completed, it shall determine the value of the corresponding wide
character and then, if pwc is not a null pointer, shall store that
value in the object pointed to by pwc. If the corresponding wide
character is the null wide character, the resulting state described
shall be the initial conversion state.
If ps is a null pointer, the mbrtowc() function shall use its own
internal mbstate_t object, which shall be 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 mbrtowc().
The behavior of this function is affected by the LC_CTYPE category of
the current locale.
The mbrtowc() function need not be thread-safe if called with a NULL
ps argument.
The mbrtowc() function shall not change the setting of errno if
successful.
The mbrtowc() function shall return the first of the following that
applies:
0 If the next n or fewer bytes complete the character that
corresponds to the null wide character (which is the
value stored).
between 1 and n inclusive
If the next n or fewer bytes complete a valid character
(which is the value stored); the value returned shall be
the number of bytes that complete the character.
(size_t)−2 If the next n bytes contribute to an incomplete but
potentially valid character, and all n bytes have been
processed (no value is stored). When n has at least the
value of the {MB_CUR_MAX} macro, this case can only occur
if s points at a sequence of redundant shift sequences
(for implementations with state-dependent encodings).
(size_t)−1 If an encoding error occurs, in which case the next n or
fewer bytes do not contribute to a complete and valid
character (no value is stored). In this case, [EILSEQ]
shall be stored in errno and the conversion state is
undefined.
The mbrtowc() function shall fail if:
EILSEQ An invalid character sequence is detected.
The mbrtowc() function may fail if:
EINVAL ps points to an object that contains an invalid conversion
state.
The following sections are informative.
None.
None.
None.
None.
mbsinit(3p), mbsrtowcs(3p)
The Base Definitions volume of POSIX.1‐2008, wchar.h(0p)
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 .
IEEE/The Open Group 2013 MBRTOWC(3P)
Pages that refer to this page: wchar.h(0p), fwprintf(3p), mbrlen(3p), mbsinit(3p), mbsrtowcs(3p)