1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
|
.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
.\"
.\" %%%LICENSE_START(GPLv2+_DOC_ONEPARA)
.\" This is free documentation; you can redistribute it and/or
.\" modify it under the terms of the GNU General Public License as
.\" published by the Free Software Foundation; either version 2 of
.\" the License, or (at your option) any later version.
.\" %%%LICENSE_END
.\"
.\" References consulted:
.\" GNU glibc-2 source code and manual
.\" Dinkumware C library reference http://www.dinkumware.com/
.\" OpenGroup's Single UNIX specification
.\" http://www.UNIX-systems.org/online.html
.\" ISO/IEC 9899:1999
.\"
.TH MBRTOWC 3 2015-08-08 "GNU" "Linux Programmer's Manual"
.SH NAME
mbrtowc \- convert a multibyte sequence to a wide character
.SH SYNOPSIS
.nf
.B #include <wchar.h>
.sp
.BI "size_t mbrtowc(wchar_t *" pwc ", const char *" s ", size_t " n \
", mbstate_t *" ps );
.fi
.SH DESCRIPTION
The main case for this function is when
.IR s
is not NULL and
.I pwc
is
not NULL.
In this case, the
.BR mbrtowc ()
function inspects at most
.I n
bytes of the multibyte string starting at
.IR s ,
extracts the next complete
multibyte character, converts it to a wide character and stores it at
.IR *pwc .
It updates the shift state
.IR *ps .
If the converted wide
character is not L\(aq\\0\(aq (the null wide character),
it returns the number of bytes that were consumed
from
.IR s .
If the converted wide character is L\(aq\\0\(aq, it resets the shift
state
.I *ps
to the initial state and returns 0.
.PP
If the
.IR n
bytes starting at
.I s
do not contain a complete multibyte
character,
.BR mbrtowc ()
returns
.IR "(size_t)\ \-2" .
This can happen even if
.I n
>=
.IR MB_CUR_MAX ,
if the multibyte string contains redundant shift
sequences.
.PP
If the multibyte string starting at
.I s
contains an invalid multibyte
sequence before the next complete character,
.BR mbrtowc ()
returns
.IR "(size_t)\ \-1"
and sets
.I errno
to
.BR EILSEQ .
In this case,
the effects on
.I *ps
are undefined.
.PP
A different case is when
.IR s
is not NULL but
.I pwc
is NULL.
In this case, the
.BR mbrtowc ()
function behaves as above, except that it does not
store the converted wide character in memory.
.PP
A third case is when
.I s
is NULL.
In this case,
.IR pwc
and
.I n
are
ignored.
If the conversion state represented by
.I *ps
denotes an
incomplete multibyte character conversion, the
.BR mbrtowc ()
function
returns
.IR "(size_t)\ \-1" ,
sets
.I errno
to
.BR EILSEQ ,
and
leaves
.I *ps
in an undefined state.
Otherwise, the
.BR mbrtowc ()
function
puts
.I *ps
in the initial state and returns 0.
.PP
In all of the above cases, if
.I ps
is NULL, a static anonymous
state known only to the
.BR mbrtowc ()
function is used instead.
Otherwise,
.IR *ps
must be a valid
.I mbstate_t
object.
An
.IR mbstate_t
object
.I a
can be initialized to the initial state
by zeroing it, for example using
.sp
.in +4n
memset(&a, 0, sizeof(a));
.in
.SH RETURN VALUE
The
.BR mbrtowc ()
function returns the number of bytes parsed from the
multibyte sequence starting at
.IR s ,
if a non-L\(aq\\0\(aq wide character
was recognized.
It returns 0, if a L\(aq\\0\(aq wide character was recognized.
It returns
.I (size_t)\ \-1
and sets
.I errno
to
.BR EILSEQ ,
if an invalid multibyte sequence was
encountered.
It returns
.I "(size_t)\ \-2"
if it couldn't parse a complete multibyte
character, meaning that
.I n
should be increased.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lb lb lb
l l l.
Interface Attribute Value
T{
.BR mbrtowc ()
T} Thread safety MT-Unsafe race:mbrtowc/!ps
.TE
.SH CONFORMING TO
POSIX.1-2001, POSIX.1-2008, C99.
.SH NOTES
The behavior of
.BR mbrtowc ()
depends on the
.B LC_CTYPE
category of the
current locale.
.SH SEE ALSO
.BR mbsinit (3),
.BR mbsrtowcs (3)
.SH COLOPHON
This page is part of release 4.10 of the Linux
.I man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
\%https://www.kernel.org/doc/man\-pages/.
|
