int
mblen(
const char *s
, size_t n
)
)
function usually determines the number of bytes in
a multibyte character pointed to by
s
and returns it.
This function shall only examine max n bytes of the array beginning from
s
.
In state-dependent encodings,
s
may point the special sequence bytes to change the shift-state.
Although such sequence bytes corresponds to no individual
wide-character code,
the
mblen()
changes the own state by them and treats them
as if they are a part of the subsequent multibyte character.
Unlike
mbrlen(3),
the first
n
bytes pointed to by
s
need to form an entire multibyte character.
Otherwise, this function causes an error.
mblen()
is equivalent to the following call, except the internal state of the
mbtowc(3)
function is not affected:
mbtowc(NULL, s, n);
Calling any other functions in
Standard C Library (libc, -lc)
never changes the internal
state of
mblen(),
except for calling
setlocale(3)
with the
LC_CTYPE
category changed to that of the current locale.
Such
setlocale(3)
calls cause the internal state of this function to be indeterminate.
The behaviour of
mblen()
is affected by the
LC_CTYPE
category of the current locale.
These are the special cases:
)
initializes its own internal state to an initial state, and
determines whether the current encoding is state-dependent.
This function returns 0 if the encoding is state-independent,
otherwise non-zero.
n
bytes of the array pointed to by
s
never form a complete character.
Thus,
mblen(
)
always fails.
)
returns:
s
points to a nul byte
(`\0').
s
.
There are no cases that this value is greater than
n
or the value of the
MB_CUR_MAX
macro.
s
points to an invalid or incomplete multibyte character.
The
mblen(
)
also sets
errno
to indicate the error.
When
s
is equal to
NULL
,
the
mblen()
returns:
)
may cause an error in the following case:
EILSEQ
]
s
points to an invalid or incomplete multibyte character.
)
function conforms to
ANSI X3.159-1989 (``ANSI C89'') .