MBLEN(P) POSIX Programmer's Manual MBLEN(P)NAMEmblen - 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 vol‐
ume 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 func‐
tion 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 con‐
stitute the character (if the next n or fewer bytes form a valid char‐
acter), 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 ALSOmbtowc() , 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 .
IEEE/The Open Group 2003 MBLEN(P)
