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

6       mbtowc - convert a multibyte sequence to a wide character
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SYNOPSIS

9       #include <stdlib.h>
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11       int mbtowc(wchar_t *restrict pwc, const char *restrict s, size_t n);
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DESCRIPTION

14       The  main  case  for this function is when s is not NULL and pwc is not
15       NULL.  In this case, the mbtowc() function inspects at most n bytes  of
16       the  multibyte  string starting at s, extracts the next complete multi‐
17       byte character, converts it to a wide character and stores it at  *pwc.
18       It updates an internal shift state known only to the mbtowc() function.
19       If s does not point to a null byte ('\0'), it  returns  the  number  of
20       bytes that were consumed from s, otherwise it returns 0.
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22       If  the n bytes starting at s do not contain a complete multibyte char‐
23       acter, or if they contain an invalid multibyte sequence,  mbtowc()  re‐
24       turns  -1.   This  can happen even if n >= MB_CUR_MAX, if the multibyte
25       string contains redundant shift sequences.
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27       A different case is when s is not NULL but pwc is NULL.  In this  case,
28       the  mbtowc()  function behaves as above, except that it does not store
29       the converted wide character in memory.
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31       A third case is when s is NULL.  In this case, pwc and n  are  ignored.
32       The  mbtowc() function resets the shift state, only known to this func‐
33       tion, to the initial state, and returns nonzero  if  the  encoding  has
34       nontrivial shift state, or zero if the encoding is stateless.
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RETURN VALUE

37       If  s is not NULL, the mbtowc() function returns the number of consumed
38       bytes starting at s, or 0 if s points to a null byte, or -1 upon  fail‐
39       ure.
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41       If s is NULL, the mbtowc() function returns nonzero if the encoding has
42       nontrivial shift state, or zero if the encoding is stateless.
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ATTRIBUTES

45       For an  explanation  of  the  terms  used  in  this  section,  see  at‐
46       tributes(7).
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48       ┌─────────────────────────────────────┬───────────────┬────────────────┐
49       │Interface                            │ Attribute     │ Value          │
50       ├─────────────────────────────────────┼───────────────┼────────────────┤
51       │mbtowc()                             │ Thread safety │ MT-Unsafe race │
52       └─────────────────────────────────────┴───────────────┴────────────────┘
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CONFORMING TO

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

58       The  behavior  of mbtowc() depends on the LC_CTYPE category of the cur‐
59       rent locale.
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61       This function is not multithread safe.  The  function  mbrtowc(3)  pro‐
62       vides a better interface to the same functionality.
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SEE ALSO

65       MB_CUR_MAX(3),  mblen(3),  mbrtowc(3),  mbstowcs(3),  wcstombs(3),  wc‐
66       tomb(3)
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COLOPHON

69       This page is part of release 5.13 of the Linux  man-pages  project.   A
70       description  of  the project, information about reporting bugs, and the
71       latest    version    of    this    page,    can     be     found     at
72       https://www.kernel.org/doc/man-pages/.
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76GNU                               2021-03-22                         MBTOWC(3)
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