1MBRTOWC(P) POSIX Programmer's Manual MBRTOWC(P)
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6 mbrtowc - convert a character to a wide-character code (restartable)
7
9 #include <wchar.h>
10 size_t mbrtowc(wchar_t *restrict pwc, const char *restrict s,
12 size_t n, mbstate_t *restrict ps);
13
16 If s is a null pointer, the mbrtowc() function shall be equivalent to
17 the call:
18 mbrtowc(NULL, "", 1, ps)
21 In this case, the values of the arguments pwc and n are ignored.
23 If s is not a null pointer, the mbrtowc() function shall inspect at
25 most n bytes beginning at the byte pointed to by s to determine the
26 number of bytes needed to complete the next character (including any
27 shift sequences). If the function determines that the next character is
28 completed, it shall determine the value of the corresponding wide char‐
29 acter and then, if pwc is not a null pointer, shall store that value in
30 the object pointed to by pwc. If the corresponding wide character is
31 the null wide character, the resulting state described shall be the
32 initial conversion state.
33 If ps is a null pointer, the mbrtowc() function shall use its own
35 internal mbstate_t object, which shall be initialized at program start-
36 up to the initial conversion state. Otherwise, the mbstate_t object
37 pointed to by ps shall be used to completely describe the current con‐
38 version state of the associated character sequence. The implementation
39 shall behave as if no function defined in this volume of
40 IEEE Std 1003.1-2001 calls mbrtowc().
41 The behavior of this function is affected by the LC_CTYPE category of
43 the current locale.
44
46 The mbrtowc() function shall return the first of the following that
47 applies:
48 0 If the next n or fewer bytes complete the character that corre‐
50 sponds to the null wide character (which is the value stored).
51 between 1 and n inclusive
53 If the next n or fewer bytes complete a valid character (which
55 is the value stored); the value returned shall be the number of
56 bytes that complete the character.
57 (size_t)-2
59 If the next n bytes contribute to an incomplete but potentially
60 valid character, and all n bytes have been processed (no value
61 is stored). When n has at least the value of the {MB_CUR_MAX}
62 macro, this case can only occur if s points at a sequence of
63 redundant shift sequences (for implementations with state-depen‐
64 dent encodings).
65 (size_t)-1
67 If an encoding error occurs, in which case the next n or fewer
68 bytes do not contribute to a complete and valid character (no
69 value is stored). In this case, [EILSEQ] shall be stored in
70 errno and the conversion state is undefined.
71
74 The mbrtowc() function may fail if:
75 EINVAL ps points to an object that contains an invalid conversion
77 state.
78 EILSEQ Invalid character sequence is detected.
80 The following sections are informative.
83
85 None.
86
88 None.
89
91 None.
92
94 None.
95
97 mbsinit() , the Base Definitions volume of IEEE Std 1003.1-2001,
98 <wchar.h>
99
101 Portions of this text are reprinted and reproduced in electronic form
102 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
103 -- Portable Operating System Interface (POSIX), The Open Group Base
104 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
105 Electrical and Electronics Engineers, Inc and The Open Group. In the
106 event of any discrepancy between this version and the original IEEE and
107 The Open Group Standard, the original IEEE and The Open Group Standard
108 is the referee document. The original Standard can be obtained online
109 at http://www.opengroup.org/unix/online.html .
110IEEE/The Open Group 2003 MBRTOWC(P)