NAME

       mbrtowc - convert a character to a wide-character code (restartable)

SYNOPSIS

       #include <wchar.h>

       size_t mbrtowc(wchar_t *restrict pwc, const char *restrict s,
              size_t n, mbstate_t *restrict ps);

DESCRIPTION

       If s is a null pointer, the mbrtowc() function shall be equivalent to the call:

              mbrtowc(NULL, "", 1, ps)

       In this case, the values of the arguments pwc and n are ignored.

       If  s  is  not a null pointer, the mbrtowc() function shall inspect at most n bytes beginning at the byte
       pointed to by s to determine the number of bytes needed to complete the  next  character  (including  any
       shift sequences). If the function determines that the next character is completed, it shall determine the
       value  of the corresponding wide character and then, if pwc is not a null pointer, shall store that value
       in the object pointed to by pwc. If the corresponding wide character is  the  null  wide  character,  the
       resulting state described shall be the initial conversion state.

       If  ps is a null pointer, the mbrtowc() function shall use its own internal mbstate_t object, which shall
       be initialized at program start-up to the initial  conversion  state.  Otherwise,  the  mbstate_t  object
       pointed  to  by  ps  shall  be used to completely describe the current conversion state of the associated
       character sequence. The implementation shall  behave  as  if  no  function  defined  in  this  volume  of
       IEEE Std 1003.1-2001 calls mbrtowc().

       The behavior of this function is affected by the LC_CTYPE category of the current locale.

RETURN VALUE

       The mbrtowc() function shall return the first of the following that applies:

       0      If  the  next  n or fewer bytes complete the character that corresponds to the null wide character
              (which is the value stored).

       between 1 and n inclusive

              If the next n or fewer bytes complete a valid character (which is the  value  stored);  the  value
              returned shall be the number of bytes that complete the character.

       (size_t)-2
              If  the  next n bytes contribute to an incomplete but potentially valid character, and all n bytes
              have been processed (no value is stored). When n has at least the value of the {MB_CUR_MAX} macro,
              this case  can  only  occur  if  s  points  at  a  sequence  of  redundant  shift  sequences  (for
              implementations with state-dependent encodings).

       (size_t)-1
              If  an  encoding  error  occurs,  in  which  case the next n or fewer bytes do not contribute to a
              complete and valid character (no value is stored). In this case, [EILSEQ] shall be stored in errno
              and the conversion state is undefined.

ERRORS

       The mbrtowc() function may fail if:

       EINVAL ps points to an object that contains an invalid conversion state.

       EILSEQ Invalid character sequence is detected.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       mbsinit() , the Base Definitions volume of IEEE Std 1003.1-2001, <wchar.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                                            MBRTOWC(P)