1MBTOWC(3) Linux Programmer's Manual MBTOWC(3)
2
3
4
6 mbtowc - convert a multibyte sequence to a wide character
7
9 #include <stdlib.h>
10
11 int mbtowc(wchar_t *restrict pwc, const char *restrict s, size_t n);
12
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.
21
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.
26
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.
30
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.
35
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.
40
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.
43
45 For an explanation of the terms used in this section, see at‐
46 tributes(7).
47
48 ┌─────────────────────────────────────┬───────────────┬────────────────┐
49 │Interface │ Attribute │ Value │
50 ├─────────────────────────────────────┼───────────────┼────────────────┤
51 │mbtowc() │ Thread safety │ MT-Unsafe race │
52 └─────────────────────────────────────┴───────────────┴────────────────┘
53
55 POSIX.1-2001, POSIX.1-2008, C99.
56
58 The behavior of mbtowc() depends on the LC_CTYPE category of the cur‐
59 rent locale.
60
61 This function is not multithread safe. The function mbrtowc(3) pro‐
62 vides a better interface to the same functionality.
63
65 MB_CUR_MAX(3), mblen(3), mbrtowc(3), mbstowcs(3), wcstombs(3), wc‐
66 tomb(3)
67
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/.
73
74
75
76GNU 2021-03-22 MBTOWC(3)