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 implemenation 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 enivronment 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.


June 21, 2014 MBRLEN(3C)