mbsrtowcs(3)

1MBSRTOWCS(3)               Linux Programmer's Manual              MBSRTOWCS(3)
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NAME

6       mbsrtowcs - convert a multibyte string to a wide-character string
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SYNOPSIS

9       #include <wchar.h>
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11       size_t mbsrtowcs(wchar_t *restrict dest, const char **restrict src,
12                        size_t len, mbstate_t *restrict ps);
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DESCRIPTION

15       If  dest  is  not NULL, the mbsrtowcs() function converts the multibyte
16       string *src to a wide-character string starting at dest.  At  most  len
17       wide  characters  are written to dest.  The shift state *ps is updated.
18       The conversion is effectively  performed  by  repeatedly  calling  mbr‐
19       towc(dest,  *src,  n,  ps)  where n is some positive number, as long as
20       this call succeeds, and then incrementing dest by one and *src  by  the
21       number of bytes consumed.  The conversion can stop for three reasons:
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23       1. An  invalid  multibyte sequence has been encountered.  In this case,
24          *src is left pointing to the invalid multibyte sequence, (size_t) -1
25          is returned, and errno is set to EILSEQ.
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27       2. len  non-L'\0'  wide  characters  have been stored at dest.  In this
28          case, *src is left pointing to the next  multibyte  sequence  to  be
29          converted,  and the number of wide characters written to dest is re‐
30          turned.
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32       3. The multibyte string has been completely  converted,  including  the
33          terminating null wide character ('\0'), which has the side effect of
34          bringing back *ps to the initial state.  In this case, *src  is  set
35          to  NULL, and the number of wide characters written to dest, exclud‐
36          ing the terminating null wide character, is returned.
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38       If dest is NULL, len is ignored, and the conversion proceeds as  above,
39       except  that  the converted wide characters are not written out to mem‐
40       ory, and that no length limit exists.
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42       In both of the above cases, if ps is NULL,  a  static  anonymous  state
43       known only to the mbsrtowcs() function is used instead.
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45       The  programmer  must  ensure  that there is room for at least len wide
46       characters at dest.
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RETURN VALUE

49       The mbsrtowcs() function returns the number  of  wide  characters  that
50       make  up the converted part of the wide-character string, not including
51       the terminating null wide character.  If an invalid multibyte  sequence
52       was encountered, (size_t) -1 is returned, and errno set to EILSEQ.
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ATTRIBUTES

55       For  an  explanation  of  the  terms  used  in  this  section,  see at‐
56       tributes(7).
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58       ┌────────────┬───────────────┬─────────────────────────────────────────┐
59       │Interface   │ Attribute     │ Value                                   │
60       ├────────────┼───────────────┼─────────────────────────────────────────┤
61       │mbsrtowcs() │ Thread safety │ MT-Unsafe race:mbsrtowcs/!ps            │
62       └────────────┴───────────────┴─────────────────────────────────────────┘
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CONFORMING TO

65       POSIX.1-2001, POSIX.1-2008, C99.
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NOTES

68       The behavior of mbsrtowcs() depends on the  LC_CTYPE  category  of  the
69       current locale.
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71       Passing NULL as ps is not multithread safe.
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COLOPHON

77       This  page  is  part of release 5.13 of the Linux man-pages project.  A
78       description of the project, information about reporting bugs,  and  the
79       latest     version     of     this    page,    can    be    found    at
80       https://www.kernel.org/doc/man-pages/.
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84GNU                               2021-03-22                      MBSRTOWCS(3)