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1 .\" $NetBSD: mbsrtowcs.3,v 1.12 2010/12/16 17:42:27 wiz Exp $
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27 .Dd February 4, 2002
28 .Dt MBSRTOWCS 3
29 .Os
30 .\" ----------------------------------------------------------------------
31 .Sh NAME
32 .Nm mbsrtowcs
33 .Nd converts a multibyte character string to a wide-character string \
34 (restartable)
35 .\" ----------------------------------------------------------------------
36 .Sh LIBRARY
37 .Lb libc
38 .\" ----------------------------------------------------------------------
39 .Sh SYNOPSIS
40 .In wchar.h
41 .Ft size_t
42 .Fn mbsrtowcs "wchar_t * restrict pwcs" "const char ** restrict s" "size_t n" \
43 "mbstate_t * restrict ps"
44 .\" ----------------------------------------------------------------------
45 .Sh DESCRIPTION
46 The
47 .Fn mbsrtowcs
48 converts the multibyte character string indirectly pointed to by
49 .Fa s
50 to the corresponding wide-character string, and stores it in the
51 array pointed to by
52 .Fa pwcs .
53 The conversion stops due to the following reasons:
54 .Bl -bullet
55 .It
56 The conversion reaches a nul byte.
57 In this case, the nul byte is also converted.
58 .It
59 The
60 .Fn mbsrtowcs
61 has already stored
62 .Fa n
63 wide characters.
64 .It
65 The conversion encounters an invalid character.
66 .El
67 .Pp
68 Each character will be converted as if
69 .Xr mbrtowc 3
70 is continuously called.
71 .Pp
72 After conversion,
73 if
74 .Fa pwcs
75 is not a null pointer,
76 the pointer object pointed to by
77 .Fa s
78 is a null pointer (if the conversion is stopped due to reaching a
79 nul byte) or the first byte of the character just after the last
80 character converted.
81 .Pp
82 If
83 .Fa pwcs
84 is not a null pointer and the conversion is stopped due to reaching
85 a nul byte, the
86 .Fn mbsrtowcs
87 places the state object pointed to by
88 .Fa ps
89 to an initial state after the conversion has taken place.
90 .Pp
91 The behaviour of
92 .Fn mbsrtowcs
93 is affected by the
94 .Dv LC_CTYPE
95 category of the current locale.
96 .Pp
97 These are the special cases:
98 .Bl -tag -width 012345678901
99 .It "s == NULL || *s == NULL"
100 Undefined (may cause the program to crash).
101 .It "pwcs == NULL"
102 The conversion has taken place, but the resulting wide-character string
103 was discarded.
104 In this case, the pointer object pointed to by
105 .Fa s
106 is not modified and
107 .Fa n
108 is ignored.
109 .It "ps == NULL"
110 The
111 .Fn mbsrtowcs
112 uses its own internal state object to keep the conversion state,
113 instead of
114 .Fa ps
115 mentioned in this manual page.
116 .Pp
117 Calling any other functions in
118 .Lb libc
119 never changes the internal state of
120 .Fn mbsrtowcs ,
121 which is initialized at startup time of the program.
122 .El
123 .\" ----------------------------------------------------------------------
124 .Sh RETURN VALUES
125 .Fn mbsrtowcs
126 returns:
127 .Bl -tag -width 012345678901
128 .It 0 or positive
129 The value returned is the number of elements stored in the array
130 pointed to by
131 .Fa pwcs ,
132 except for a terminating nul wide character (if any).
133 If
134 .Fa pwcs
135 is not
136 .Dv NULL
137 and the value returned is equal to
138 .Fa n ,
139 the wide-character string pointed to by
140 .Fa pwcs
141 is not nul-terminated.
142 If
143 .Fa pwcs
144 is a null pointer, the value returned is the number of elements to contain
145 the whole string converted, except for a terminating nul wide character.
146 .It (size_t)-1
147 The array indirectly pointed to by
148 .Fa s
149 contains a byte sequence forming invalid character.
150 In this case,
151 .Fn mbsrtowcs
152 sets
153 .Va errno
154 to indicate the error.
155 .El
156 .\" ----------------------------------------------------------------------
157 .Sh ERRORS
158 .Fn mbsrtowcs
159 may cause an error in the following case:
160 .Bl -tag -width Er
161 .It Bq Er EILSEQ
162 The pointer pointed to by
163 .Fa s
164 points to an invalid or incomplete multibyte character.
165 .It Bq Er EINVAL
166 .Fa ps
167 points to an invalid or uninitialized mbstate_t object.
168 .El
169 .\" ----------------------------------------------------------------------
170 .Sh SEE ALSO
171 .Xr mbrtowc 3 ,
172 .Xr mbstowcs 3 ,
173 .Xr setlocale 3
174 .\" ----------------------------------------------------------------------
175 .Sh STANDARDS
176 The
177 .Fn mbsrtowcs
178 function conforms to
179 .St -isoC-amd1 .
180 The restrict qualifier is added at
181 .St -isoC-99 .