MBRLEN(3C) Standard C Library Functions MBRLEN(3C)

NAME

mbrlen, mbrlen_l - 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);

#include <wchar.h>
#include <xlocale.h>

size_t mbrlen_l(const char *restrict s, size_t n, mbstate_t *restrict ps,
locale_t loc);

DESCRIPTION

If s is not a null pointer, mbrlen() and mbrlen_l() determine the
number of bytes constituting the character pointed to by s. The call

mbrlen(s, n, ps);

is equivalent to:

mbstate_t internal;
mbrtowc(NULL, s, n, ps != NULL ? ps : &internal);

If ps is a null pointer, the mbrlen() and mbrlen_l() functions use
their own internal mbstate_t object, which is initialized at program
startup to the initial conversion state. Otherwise, the mbstate_t
object pointed to by ps is used to completely describe the current
conversion state of the associated character sequence. The
implementation will behave as if no function defined in the Reference
Manual calls mbrlen().

The behavior of mbrlen() is affected by the LC_CTYPE category of the
current locale. See environ(7). The behavior of mbrlen_l() does not
use the current environment and instead uses the locale specified by
loc.

RETURN VALUES

The mbrlen() and mbrlen_l() functions 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 is 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 is stored in
errno and the conversion state is undefined.

ERRORS

The mbrlen() and mbrlen_l() functions may fail if:

EINVAL
The ps argument points to an object that contains an
invalid conversion state.


EILSEQ
Invalid character sequence is detected.

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:

+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | See below. |
+--------------------+-----------------+
|MT-Level | MT-Safe |
+--------------------+-----------------+

The mbrlen() function is Standard. The mbrlen_l() function is
Uncommitted.

SEE ALSO

mbrtowc(3C), mbsinit(3C), newlocale(3C), setlocale(3C),
attributes(7), environ(7), standards(7)

NOTES

If ps is not a null pointer, mbrlen() uses the mbstate_t object
pointed to by ps and the function can be used safely in multithreaded
applications, as long as setlocale(3C) is not being called to change
the locale or a per-thread locale has been installed on the calling
thread with uselocale(3C). If ps is a null pointer, mbrlen() uses its
internal mbstate_t object and the function is Unsafe in multithreaded
applications.

February 17, 2023 MBRLEN(3C)