MBRTOWC
Section: POSIX Programmer's Manual (P)
Updated: 2003
NAME
mbrtowc - convert a character to a wide-character code (restartable)
SYNOPSIS
#include <wchar.h>
size_t mbrtowc(wchar_t *restrict pwc, const char *restrict
s,
size_t n, mbstate_t *restrict ps);
DESCRIPTION
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 IEEE Std 1003.1-2001
calls mbrtowc().
The behavior of this function is affected by the LC_CTYPE category
of the current locale.
RETURN VALUE
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.
ERRORS
The mbrtowc() function may fail if:
- EINVAL
-
ps points to an object that contains an invalid conversion state.
- EILSEQ
-
Invalid character sequence is detected.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
None.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
mbsinit() , the Base Definitions volume of IEEE Std 1003.1-2001,
<wchar.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 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 .
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- EXAMPLES
-
- APPLICATION USAGE
-
- RATIONALE
-
- FUTURE DIRECTIONS
-
- SEE ALSO
-
- COPYRIGHT
-
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