1MBRTOWC(3P)                POSIX Programmer's Manual               MBRTOWC(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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11

NAME

13       mbrtowc — convert a character to a wide-character code (restartable)
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SYNOPSIS

16       #include <wchar.h>
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18       size_t mbrtowc(wchar_t *restrict pwc, const char *restrict s,
19           size_t n, mbstate_t *restrict ps);
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DESCRIPTION

22       The functionality described on this reference page is aligned with  the
23       ISO C  standard.  Any  conflict between the requirements described here
24       and the ISO C standard is unintentional. This  volume  of  POSIX.1‐2008
25       defers to the ISO C standard.
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27       If  s  is a null pointer, the mbrtowc() function shall be equivalent to
28       the call:
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30           mbrtowc(NULL, "", 1, ps)
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32       In this case, the values of the arguments pwc and n are ignored.
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34       If s is not a null pointer, the mbrtowc()  function  shall  inspect  at
35       most  n  bytes  beginning  at the byte pointed to by s to determine the
36       number of bytes needed to complete the next  character  (including  any
37       shift sequences). If the function determines that the next character is
38       completed, it shall determine the value of the corresponding wide char‐
39       acter and then, if pwc is not a null pointer, shall store that value in
40       the object pointed to by pwc.  If the corresponding wide  character  is
41       the  null  wide  character,  the resulting state described shall be the
42       initial conversion state.
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44       If ps is a null pointer, the  mbrtowc()  function  shall  use  its  own
45       internal mbstate_t object, which shall be initialized at program start-
46       up to the initial conversion state.  Otherwise,  the  mbstate_t  object
47       pointed  to by ps shall be used to completely describe the current con‐
48       version state of the associated character sequence. The  implementation
49       shall  behave  as if no function defined in this volume of POSIX.1‐2008
50       calls mbrtowc().
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52       The behavior of this function is affected by the LC_CTYPE  category  of
53       the current locale.
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55       The mbrtowc() function need not be thread-safe if called with a NULL ps
56       argument.
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58       The mbrtowc() function shall not change the setting of  errno  if  suc‐
59       cessful.
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RETURN VALUE

62       The  mbrtowc()  function  shall  return the first of the following that
63       applies:
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65       0           If the next n or fewer bytes complete  the  character  that
66                   corresponds  to the null wide character (which is the value
67                   stored).
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69       between 1 and n inclusive
70                   If the next n or fewer bytes  complete  a  valid  character
71                   (which  is  the  value stored); the value returned shall be
72                   the number of bytes that complete the character.
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74       (size_t)−2  If the next n bytes contribute to an incomplete but  poten‐
75                   tially valid character, and all n bytes have been processed
76                   (no value is stored). When n has at least the value of  the
77                   {MB_CUR_MAX} macro, this case can only occur if s points at
78                   a sequence of redundant shift  sequences  (for  implementa‐
79                   tions with state-dependent encodings).
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81       (size_t)−1  If  an  encoding  error occurs, in which case the next n or
82                   fewer bytes do not contribute to a complete and valid char‐
83                   acter (no value is stored). In this case, [EILSEQ] shall be
84                   stored in errno and the conversion state is undefined.
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ERRORS

87       The mbrtowc() function shall fail if:
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89       EILSEQ An invalid character sequence is detected.
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91       The mbrtowc() function may fail if:
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93       EINVAL ps points to an  object  that  contains  an  invalid  conversion
94              state.
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96       The following sections are informative.
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EXAMPLES

99       None.
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APPLICATION USAGE

102       None.
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RATIONALE

105       None.
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FUTURE DIRECTIONS

108       None.
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SEE ALSO

111       mbsinit(), mbsrtowcs()
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113       The Base Definitions volume of POSIX.1‐2008, <wchar.h>
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116       Portions  of  this text are reprinted and reproduced in electronic form
117       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
118       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
119       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
120       cal  and  Electronics  Engineers,  Inc  and  The  Open Group.  (This is
121       POSIX.1-2008 with the 2013 Technical Corrigendum  1  applied.)  In  the
122       event of any discrepancy between this version and the original IEEE and
123       The Open Group Standard, the original IEEE and The Open Group  Standard
124       is  the  referee document. The original Standard can be obtained online
125       at http://www.unix.org/online.html .
126
127       Any typographical or formatting errors that appear  in  this  page  are
128       most likely to have been introduced during the conversion of the source
129       files to man page format. To report such errors,  see  https://www.ker
130       nel.org/doc/man-pages/reporting_bugs.html .
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134IEEE/The Open Group                  2013                          MBRTOWC(3P)
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