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>

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 .