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 .