PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
       may differ (consult 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

       The  functionality  described  on  this  reference  page is aligned with the ISO C standard. Any conflict
       between the requirements described  here  and  the  ISO C  standard  is  unintentional.  This  volume  of
       POSIX.1‐2008 defers to the ISO C standard.

       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 POSIX.1‐2008 calls mbtowc().

       The mbtowc() function need not be thread-safe.

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  shall  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 shall fail if:

       EILSEQ An 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 POSIX.1‐2008, <stdlib.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition,
       Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open  Group  Base
       Specifications  Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers, Inc
       and The Open Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/online.html .

       Any  typographical  or formatting errors that appear in this page are most likely to have been introduced
       during  the  conversion  of  the  source  files  to  man  page  format.  To  report  such   errors,   see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .