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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>


       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 .