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 .

IEEE/The Open Group                                   2003                                              MBLEN(P)