xref: /netbsd-src/lib/libc/locale/wcrtomb.3 (revision a5847cc334d9a7029f6352b847e9e8d71a0f9e0c)
1.\" $NetBSD: wcrtomb.3,v 1.9 2007/02/20 08:33:25 wiz Exp $
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3.\" Copyright (c)2002 Citrus Project,
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27.Dd February 4, 2002
28.Dt WCRTOMB 3
29.Os
30.\" ----------------------------------------------------------------------
31.Sh NAME
32.Nm wcrtomb
33.Nd converts a wide character to a multibyte character (restartable)
34.\" ----------------------------------------------------------------------
35.Sh LIBRARY
36.Lb libc
37.\" ----------------------------------------------------------------------
38.Sh SYNOPSIS
39.In wchar.h
40.Ft size_t
41.Fn wcrtomb "char * restrict s" "wchar_t wc" "mbstate_t * restrict ps"
42.\" ----------------------------------------------------------------------
43.Sh DESCRIPTION
44.Fn wcrtomb
45converts the wide character given by
46.Fa wc
47to the corresponding multibyte character, and stores it in the array
48pointed to by
49.Fa s
50unless
51.Fa s
52is a null pointer.
53This function will modify the first at most
54.Dv MB_CUR_MAX
55bytes of the array pointed to by
56.Fa s .
57.Pp
58The behaviour of
59.Fn wcrtomb
60is affected by the
61.Dv LC_CTYPE
62category of the current locale.
63.Pp
64These are the special cases:
65.Bl -tag -width 012345678901
66.It "wc == 0"
67For state-dependent encodings,
68.Fn wcrtomb
69stores a nul byte preceded by special byte sequence (if any)
70to return to an initial state in the array pointed to by
71.Fa s ,
72and the state object pointed to by
73.Fa ps
74also returns to an initial state.
75.It "s == NULL"
76.Fn wcrtomb
77just places
78.Fa ps
79into an initial state.
80It is equivalent to the following call:
81.Bd -literal -offset indent
82wcrtomb(buf, L'\\0', ps);
83.Ed
84.Pp
85Here,
86.Fa buf
87is a dummy buffer.
88In this case,
89.Fa wc
90is ignored.
91.It "ps == NULL"
92.Fn mbrtowc
93uses its own internal state object to keep the conversion state,
94instead of
95.Fa ps
96mentioned in this manual page.
97.Pp
98Calling any other functions in
99.Lb libc
100never changes the internal
101state of
102.Fn mbrtowc ,
103which is initialized at startup time of the program.
104.El
105.\" ----------------------------------------------------------------------
106.Sh RETURN VALUES
107.Fn wcrtomb
108returns:
109.Bl -tag -width 012345678901
110.It "positive"
111The number of bytes (including any shift sequences)
112which are stored in the array.
113.It "(size_t)-1"
114.Fa wc
115is not a valid wide character.
116In this case,
117.Fn wcrtomb
118also sets
119.Va errno
120to indicate the error.
121.El
122.\" ----------------------------------------------------------------------
123.Sh ERRORS
124.Fn wcrtomb
125may cause an error in the following case:
126.Bl -tag -width Er
127.It Bq Er EILSEQ
128.Fa wc
129is not a valid wide character.
130.It Bq Er EINVAL
131.Fa ps
132points to an invalid or uninitialized mbstate_t object.
133.El
134.\" ----------------------------------------------------------------------
135.Sh SEE ALSO
136.Xr setlocale 3 ,
137.Xr wctomb 3
138.\" ----------------------------------------------------------------------
139.Sh STANDARDS
140The
141.Fn wcrtomb
142function conforms to
143.St -isoC-amd1 .
144The restrict qualifier is added at
145.St -isoC-99 .
146