[thirdparty/man-pages.git] / man3 / mbtowc.3

.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
.\"
.\" 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.
.\"
.\" 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 MBTOWC 3  2001-07-04 "GNU" "Linux Programmer's Manual"
.SH NAME
mbtowc \- convert a multibyte sequence to a wide character
.SH SYNOPSIS
.nf
.B #include <stdlib.h>
.sp
.BI "int mbtowc(wchar_t *" pwc ", const char *" s ", size_t " n );
.fi
.SH DESCRIPTION
The main case for this function is when \fIs\fP is not NULL and \fIpwc\fP is
not NULL.
In this case, the
.BR mbtowc ()
function inspects at most \fIn\fP
bytes of the multibyte string starting at \fIs\fP,
extracts the next complete
multibyte character, converts it to a wide character and stores it at
\fI*pwc\fP.
It updates an internal shift state only known to the mbtowc
function.
If \fIs\fP does not point to a '\\0' byte, it returns the number
of bytes that were consumed from \fIs\fP, otherwise it returns 0.
.PP
If the \fIn\fP bytes starting at \fIs\fP do not contain a complete multibyte
character, or if they contain an invalid multibyte sequence,
.BR mbtowc ()
returns \-1.
This can happen even if \fIn\fP >= \fIMB_CUR_MAX\fP,
if the multibyte string contains redundant shift sequences.
.PP
A different case is when \fIs\fP is not NULL but \fIpwc\fP is NULL.
In this
case the
.BR mbtowc ()
function behaves as above, excepts that it does not
store the converted wide character in memory.
.PP
A third case is when \fIs\fP is NULL.
In this case, \fIpwc\fP and \fIn\fP are
ignored.
The
.BR mbtowc ()
function
.\" The Dinkumware doc and the Single Unix specification say this, but
.\" glibc doesn't implement this.
resets the shift state, only known to this function,
to the initial state, and
returns non-zero if the encoding has non-trivial shift state, or zero if the
encoding is stateless.
.SH "RETURN VALUE"
If \fIs\fP is not NULL, the
.BR mbtowc ()
function returns the number of
consumed bytes starting at \fIs\fP, or 0 if \fIs\fP points to a null byte,
or \-1 upon failure.
.PP
If \fIs\fP is NULL, the
.BR mbtowc ()
function
returns non-zero if the encoding
has non-trivial shift state, or zero if the encoding is stateless.
.SH "CONFORMING TO"
C99
.SH NOTES
The behaviour of
.BR mbtowc ()
depends on the LC_CTYPE category of the
current locale.
.PP
This function is not multi-thread safe.
The function
.BR mbrtowc (3)
provides
a better interface to the same functionality.
.SH "SEE ALSO"
.BR MB_CUR_MAX (3),
.BR mbrtowc (3),
.BR mbstowcs (3)
Commit	Line	Data
	1	.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
	2	.\"
	3	.\" This is free documentation; you can redistribute it and/or
	4	.\" modify it under the terms of the GNU General Public License as
	5	.\" published by the Free Software Foundation; either version 2 of
	6	.\" the License, or (at your option) any later version.
	7	.\"
	8	.\" References consulted:
	9	.\" GNU glibc-2 source code and manual
	10	.\" Dinkumware C library reference http://www.dinkumware.com/
	11	.\" OpenGroup's Single Unix specification http://www.UNIX-systems.org/online.html
	12	.\" ISO/IEC 9899:1999
	13	.\"
	14	.TH MBTOWC 3 2001-07-04 "GNU" "Linux Programmer's Manual"
	15	.SH NAME
	16	mbtowc \- convert a multibyte sequence to a wide character
	17	.SH SYNOPSIS
	18	.nf
	19	.B #include <stdlib.h>
	20	.sp
	21	.BI "int mbtowc(wchar_t " pwc ", const char " s ", size_t " n );
	22	.fi
	23	.SH DESCRIPTION
	24	The main case for this function is when \fIs\fP is not NULL and \fIpwc\fP is
	25	not NULL.
	26	In this case, the
	27	.BR mbtowc ()
	28	function inspects at most \fIn\fP
	29	bytes of the multibyte string starting at \fIs\fP,
	30	extracts the next complete
	31	multibyte character, converts it to a wide character and stores it at
	32	\fI*pwc\fP.
	33	It updates an internal shift state only known to the mbtowc
	34	function.
	35	If \fIs\fP does not point to a '\\0' byte, it returns the number
	36	of bytes that were consumed from \fIs\fP, otherwise it returns 0.
	37	.PP
	38	If the \fIn\fP bytes starting at \fIs\fP do not contain a complete multibyte
	39	character, or if they contain an invalid multibyte sequence,
	40	.BR mbtowc ()
	41	returns \-1.
	42	This can happen even if \fIn\fP >= \fIMB_CUR_MAX\fP,
	43	if the multibyte string contains redundant shift sequences.
	44	.PP
	45	A different case is when \fIs\fP is not NULL but \fIpwc\fP is NULL.
	46	In this
	47	case the
	48	.BR mbtowc ()
	49	function behaves as above, excepts that it does not
	50	store the converted wide character in memory.
	51	.PP
	52	A third case is when \fIs\fP is NULL.
	53	In this case, \fIpwc\fP and \fIn\fP are
	54	ignored.
	55	The
	56	.BR mbtowc ()
	57	function
	58	.\" The Dinkumware doc and the Single Unix specification say this, but
	59	.\" glibc doesn't implement this.
	60	resets the shift state, only known to this function,
	61	to the initial state, and
	62	returns non-zero if the encoding has non-trivial shift state, or zero if the
	63	encoding is stateless.
	64	.SH "RETURN VALUE"
	65	If \fIs\fP is not NULL, the
	66	.BR mbtowc ()
	67	function returns the number of
	68	consumed bytes starting at \fIs\fP, or 0 if \fIs\fP points to a null byte,
	69	or \-1 upon failure.
	70	.PP
	71	If \fIs\fP is NULL, the
	72	.BR mbtowc ()
	73	function
	74	returns non-zero if the encoding
	75	has non-trivial shift state, or zero if the encoding is stateless.
	76	.SH "CONFORMING TO"
	77	C99
	78	.SH NOTES
	79	The behaviour of
	80	.BR mbtowc ()
	81	depends on the LC_CTYPE category of the
	82	current locale.
	83	.PP
	84	This function is not multi-thread safe.
	85	The function
	86	.BR mbrtowc (3)
	87	provides
	88	a better interface to the same functionality.
	89	.SH "SEE ALSO"
	90	.BR MB_CUR_MAX (3),
	91	.BR mbrtowc (3),
	92	.BR mbstowcs (3)