xref: /dragonfly/lib/libc/locale/mbrtowc.3 (revision 7d2302ac) 
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25.\" $FreeBSD: head/lib/libc/locale/mbrtowc.3 250883 2013-05-21 19:59:37Z ed $
26.\"
27.Dd May 4, 2019
28.Dt MBRTOWC 3
29.Os
30.Sh NAME
31.Nm mbrtowc ,
32.Nm mbrtowc_l ,
33.Nm mbrtoc16 ,
34.Nm mbrtoc16_l ,
35.Nm mbrtoc32 ,
36.Nm mbrtoc32_l
37.Nd "convert a character to a wide-character code (restartable)"
38.Sh LIBRARY
39.Lb libc
40.Sh SYNOPSIS
41.In wchar.h
42.Ft size_t
43.Fo mbrtowc
44.Fa "wchar_t * restrict pc" "const char * restrict s" "size_t n"
45.Fa "mbstate_t * restrict ps"
46.Fc
47.In uchar.h
48.Ft size_t
49.Fo mbrtoc16
50.Fa "char16_t * restrict pc" "const char * restrict s" "size_t n"
51.Fa "mbstate_t * restrict ps"
52.Fc
53.Ft size_t
54.Fo mbrtoc32
55.Fa "char32_t * restrict pc" "const char * restrict s" "size_t n"
56.Fa "mbstate_t * restrict ps"
57.Fc
58.In xlocale.h
59.Ft size_t
60.Fo mbrtowc_l
61.Fa "wchar_t * restrict pc" "const char * restrict s" "size_t n"
62.Fa "mbstate_t * restrict ps" "locale_t locale"
63.Fc
64.Ft size_t
65.Fo mbrtoc16_l
66.Fa "char16_t * restrict pc" "const char * restrict s" "size_t n"
67.Fa "mbstate_t * restrict ps" "locale_t locale"
68.Fc
69.Ft size_t
70.Fo mbrtoc32_l
71.Fa "char32_t * restrict pc" "const char * restrict s" "size_t n"
72.Fa "mbstate_t * restrict ps" "locale_t locale"
73.Fc
74.Sh DESCRIPTION
75The
76.Fn mbrtowc ,
77.Fn mbrtowc_l ,
78.Fn mbrtoc16 ,
79.Fn mbrtoc16_l ,
80.Fn mbrtoc32 ,
81and
82.Fn mbrtoc32_l
83functions inspect at most
84.Fa n
85bytes pointed to by
86.Fa s
87to determine the number of bytes needed to complete the next multibyte
88character.
89If a character can be completed, and
90.Fa pc
91is not
92.Dv NULL ,
93the wide character which is represented by
94.Fa s
95is stored in the
96.Vt wchar_t ,
97.Vt char16_t
98or
99.Vt char32_t
100it points to.
101.Pp
102If
103.Fa s
104is
105.Dv NULL ,
106these functions behave as if
107.Fa pc
108was
109.Dv NULL ,
110.Fa s
111was an empty string
112.Pq Qq
113and
114.Fa n
115was 1.
116.Pp
117The
118.Vt mbstate_t
119argument,
120.Fa ps ,
121is used to keep track of the shift state.
122If it is
123.Dv NULL ,
124these functions use an internal, static
125.Vt mbstate_t
126object, which is initialized to the initial conversion state
127at program startup.
128.Pp
129As a single
130.Vt char16_t
131is not large enough to represent certain multibyte characters, the
132.Fn mbrtoc16
133function may need to be invoked multiple times to convert a single
134multibyte character sequence.
135.Pp
136The
137.Fn mbrtowc_l ,
138.Fn mbrtoc16_l ,
139and
140.Fn mbrtoc32_l
141functions take an explicit
142.Fa locale
143argument, whereas the
144.Fn mbrtowc ,
145.Fn mbrtoc16 ,
146and
147.Fn mbrtoc32
148functions use the current global or per-thread locale.
149.Sh RETURN VALUES
150The
151.Fn mbrtowc ,
152.Fn mbrtowc_l ,
153.Fn mbrtoc16 ,
154.Fn mbrtoc16_l ,
155.Fn mbrtoc32 ,
156and
157.Fn mbrtoc32_l
158functions return:
159.Bl -tag -width indent
160.It 0
161The next
162.Fa n
163or fewer bytes
164represent the null wide character
165.Pq Li "L'\e0'" .
166.It >0
167The next
168.Fa n
169or fewer bytes represent a valid character, these functions
170return the number of bytes used to complete the multibyte character.
171.It Po Vt size_t Pc Ns \-1
172An encoding error has occurred.
173The next
174.Fa n
175or fewer bytes do not contribute to a valid multibyte character.
176.It Po Vt size_t Pc Ns \-2
177The next
178.Fa n
179contribute to, but do not complete, a valid multibyte character sequence,
180and all
181.Fa n
182bytes have been processed.
183.El
184.Pp
185The
186.Fn mbrtoc16
187and
188.Fn mbrtoc16_l
189functions also return:
190.Bl -tag -width indent
191.It Po Vt size_t Pc Ns \-3
192The next character resulting from a previous call has been stored.
193No bytes from the input have been consumed.
194.El
195.Sh ERRORS
196The
197.Fn mbrtowc ,
198.Fn mbrtowc_l ,
199.Fn mbrtoc16 ,
200.Fn mbrtoc16_l ,
201.Fn mbrtoc32 ,
202and
203.Fn mbrtoc32_l
204functions will fail if:
205.Bl -tag -width Er
206.It Bq Er EILSEQ
207An invalid multibyte sequence was detected.
208.It Bq Er EINVAL
209The conversion state is invalid.
210.El
211.Sh SEE ALSO
212.Xr mbtowc 3 ,
213.Xr multibyte 3 ,
214.Xr setlocale 3 ,
215.Xr wcrtomb 3 ,
216.Xr xlocale 3
217.Sh STANDARDS
218The
219.Fn mbrtowc ,
220.Fn mbrtoc16
221and
222.Fn mbrtoc32
223functions conform to
224.St -isoC-2011 .
225