MBRLEN
Section: POSIX Programmer's Manual (3P)
Updated: 2017
Page Index
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
mbrlen
--- get number of bytes in a character (restartable)
SYNOPSIS
#include <wchar.h>
size_t mbrlen(const char *restrict s, size_t n,
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.1-2017 defers to the ISO C standard.
If
s
is not a null pointer,
mbrlen()
shall determine the number of bytes constituting the character pointed
to by
s.
It shall be equivalent to:
-
mbstate_t internal;
mbrtowc(NULL, s, n, ps != NULL ? ps : &internal);
If
ps
is a null pointer, the
mbrlen()
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.1-2017 calls
mbrlen().
The behavior of this function is affected by the
LC_CTYPE
category of the current locale.
The
mbrlen()
function need not be thread-safe if called with a NULL
ps
argument.
The
mbrlen()
function shall not change the setting of
errno
if successful.
RETURN VALUE
The
mbrlen()
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.
- positive
-
If the next
n
or fewer bytes complete a valid character; 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. 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. In
this case,
[EILSEQ]
shall be stored in
errno
and the conversion state is undefined.
ERRORS
The
mbrlen()
function shall fail if:
- EILSEQ
-
An invalid character sequence is detected.
In the POSIX locale an
[EILSEQ]
error cannot occur since all byte values are valid characters.
The
mbrlen()
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(),
mbrtowc()
The Base Definitions volume of POSIX.1-2017,
<wchar.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 .