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NAME
       mbtowc - convert a character to a wide-character code


SYNOPSIS
       #include <stdlib.h>

       int mbtowc(wchar_t *restrict pwc, const char *restrict s, size_t n);


DESCRIPTION
       If  s  is  not a null pointer, mbtowc() shall determine the number of bytes that constitute the character
       pointed to by s. It shall then determine the wide-character code for  the  value  of  type  wchar_t  that
       corresponds  to  that  character. (The value of the wide-character code corresponding to the null byte is
       0.) If the character is valid and pwc is not a null pointer, mbtowc() shall store the wide-character code
       in the object pointed to by pwc.

       The  behavior  of  this function is affected by the LC_CTYPE category of the current locale. For a state-
       dependent encoding, this function is 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. At most n bytes of the array  pointed
       to by s shall be examined.

       The  implementation  shall  behave as if no function defined in this volume of IEEE Std 1003.1-2001 calls
       mbtowc().


RETURN VALUE
       If s is a  null  pointer,  mbtowc()  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, mbtowc() shall
       either return 0 (if s points to the null byte), or  return  the  number  of  bytes  that  constitute  the
       converted  character  (if  the next n or fewer bytes form a valid character), or return -1    and may set
       errno to indicate the error  (if they do not form a valid character).

       In no case shall the value returned be greater than n or the value of the {MB_CUR_MAX} macro.


ERRORS
       The mbtowc() 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
       mblen() , 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 .