xref: /openbsd/lib/libc/locale/wcrtomb.3 (revision 3d8817e4)
1.\" $OpenBSD: wcrtomb.3,v 1.4 2010/03/26 19:30:41 jmc Exp $
2.\" $NetBSD: wcrtomb.3,v 1.4 2003/09/08 17:54:31 wiz Exp $
3.\"
4.\" Copyright (c)2002 Citrus Project,
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28.Dd $Mdocdate: March 26 2010 $
29.Dt WCRTOMB 3
30.Os
31.\" ----------------------------------------------------------------------
32.Sh NAME
33.Nm wcrtomb
34.Nd converts a wide character to a multibyte character (restartable)
35.\" ----------------------------------------------------------------------
36.Sh SYNOPSIS
37.Fd #include <wchar.h>
38.Ft size_t
39.Fn wcrtomb "const char * restrict s" "wchar_t wc" "mbstate_t * restrict ps"
40.\" ----------------------------------------------------------------------
41.Sh DESCRIPTION
42.Fn wcrtomb
43converts the wide character given by
44.Fa wc
45to the corresponding multibyte character, and stores it in the array
46pointed to by
47.Fa s
48unless
49.Fa s
50is a null pointer.
51This function will modify the first at most
52.Dv MB_CUR_MAX
53bytes of the array pointed by
54.Fa s .
55.Pp
56The behaviour of
57.Fn wcrtomb
58is affected by the
59.Dv LC_CTYPE
60category of the current locale.
61.Pp
62These are the special cases:
63.Bl -tag -width 012345678901
64.It "wc == 0"
65For state-dependent encodings,
66.Fn wcrtomb
67stores a null byte preceded by a special byte sequence (if any)
68to return to an initial state to the array pointed by
69.Fa s ,
70and the state object pointed by
71.Fa ps
72also returned to an initial state.
73.It "s == NULL"
74.Fn wcrtomb
75just places
76.Fa ps
77into an initial state.
78It is equivalent to the following call:
79.Bd -literal -offset indent
80wcrtomb(buf, L'\e0', ps);
81.Ed
82.Pp
83Here,
84.Fa buf
85is a dummy buffer.
86In this case,
87.Fa wc
88is ignored.
89.It "ps == NULL"
90.Fn mbrtowc
91uses its own internal state object to keep the conversion state,
92instead of
93.Fa ps
94mentioned in this manual page.
95.Pp
96Calling any other functions in
97.Em libc
98never change the internal
99state of
100.Fn mbrtowc ,
101which is initialized at startup time of the program.
102.El
103.\" ----------------------------------------------------------------------
104.Sh RETURN VALUES
105.Fn wcrtomb
106returns:
107.Bl -tag -width 012345678901
108.It "positive"
109The number of bytes (including any shift sequences)
110which are stored in the array.
111.It "(size_t)-1"
112.Fa wc
113is not a valid wide character.
114In this case,
115.Fn wcrtomb
116also sets
117.Va errno
118to indicate error.
119.El
120.\" ----------------------------------------------------------------------
121.Sh ERRORS
122.Fn wcrtomb
123may cause an error in the following cases:
124.Bl -tag -width Er
125.It Bq Er EILSEQ
126.Fa wc
127is not a valid wide character.
128.It Bq Er EINVAL
129.Fa ps
130points to an invalid or uninitialized mbstate_t object.
131.El
132.\" ----------------------------------------------------------------------
133.Sh SEE ALSO
134.Xr setlocale 3 ,
135.Xr wctomb 3
136.\" ----------------------------------------------------------------------
137.Sh STANDARDS
138The
139.Fn wcrtomb
140function conforms to
141.\" .St -isoC-amd1 .
142ISO/IEC 9899/AMD1:1995
143.Pq Dq ISO C90, Amendment 1 .
144The restrict qualifier is added at
145.\" .St -isoC99 .
146ISO/IEC 9899/1999
147.Pq Dq ISO C99 .
148