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MBLEN(3P)                  POSIX Programmer's Manual                 MBLEN(3P)

PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the  corresponding
       Linux  manual page for details of Linux behavior), or the interface may
       not be implemented on Linux.
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  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 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 .

IEEE/The Open Group                  2003                            MBLEN(3P)