man mblen () - get number of bytes in a character

NAME

mblen - get number of bytes in a character

SYNOPSIS

#include <stdlib.h>

int mblen(const char *s, size_t n);

DESCRIPTION

If s is not a null pointer, mblen() shall determine the number of bytes constituting the character pointed to by s. Except that the shift state of mbtowc() is not affected, it shall be equivalent to: 

mbtowc((wchar_t *)0, s, n);




The implementation shall behave as if no function defined in this
volume of IEEE Std 1003.1-2001 calls
mblen().


The behavior of this function is affected by the LC_CTYPE category
of the current locale. For a state-dependent encoding,
this function shall be placed into its initial state by a call for
which its character pointer argument, s, is a null
pointer. Subsequent calls with s as other than a null pointer
shall cause the internal state of the function to be altered
as necessary. A call with s as a null pointer shall cause this
function to return a non-zero value if encodings have state
dependency, and 0 otherwise. If the implementation employs special
bytes to change the shift state, these bytes shall not produce
separate wide-character codes, but shall be grouped with an adjacent
character. Changing the LC_CTYPE category causes the
shift state of this function to be unspecified.

RETURN VALUE

If s is a null pointer, mblen() shall return a non-zero
or 0 value, if character encodings, respectively, do or do
not have state-dependent encodings. If s is not a null pointer,
mblen() shall either return 0 (if s points to
the null byte), or return the number of bytes that constitute the
character (if the next n or fewer bytes form a valid
character), or return -1 (if they do not form a valid character) 
 and may set errno to indicate the error.  In no case shall
the value returned be greater than n or the value of
the {MB_CUR_MAX} macro.

ERRORS

The mblen() function may fail if:

EILSEQ

Invalid character sequence is detected. 



The following sections are informative.

EXAMPLES

None.

APPLICATION USAGE

None.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

mbtowc() , mbstowcs() , wctomb() , wcstombs()
, the Base Definitions volume of
IEEE Std 1003.1-2001, <stdlib.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 .