MBTOWC(3P)                                          POSIX Programmer's Manual                                         MBTOWC(3P)



PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (con-
       sult the corresponding Linux manual page for details of Linux behavior), or the  interface  may  not  be  implemented  on
       Linux.

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 nec-
       essary.  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  exam-
       ined.

       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, Copy-
       right (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.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                    MBTOWC(3P)