.\" 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.
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.\" 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 MBSRTOWCS 3  1999-07-25 "GNU" "Linux Programmer's Manual"
.SH NAME
mbsrtowcs \- convert a multibyte string to a wide-character string
.SH SYNOPSIS
.nf
.B #include <wchar.h>
.sp
.BI "size_t mbsrtowcs(wchar_t *" dest ", const char **" src ,
.BI "                  size_t " len ", mbstate_t *" ps );
.fi
.SH DESCRIPTION
If \fIdest\fP is not a NULL pointer, the
.BR mbsrtowcs ()
function converts the
multibyte string \fI*src\fP to a wide-character string starting at \fIdest\fP.
At most \fIlen\fP wide characters are written to \fIdest\fP.
The shift state
\fI*ps\fP is updated.
The conversion is effectively performed by repeatedly
calling mbrtowc(\fIdest\fP,\fI*src\fP,\fIn\fP,\fIps\fP) where \fIn\fP is some
positive number, as long as this call succeeds, and then incrementing
\fIdest\fP by one and \fI*src\fP by the number of bytes consumed.
The conversion can stop for three reasons:
.PP
1. An invalid multibyte sequence has been encountered.
In this case \fI*src\fP
is left pointing to the invalid multibyte sequence, (size_t)(\-1) is returned,
and \fIerrno\fP is set to \fBEILSEQ\fP.
.PP
2. \fIlen\fP non-L'\\0' wide characters have been stored at \fIdest\fP.
In this
case \fI*src\fP is left pointing to the next multibyte sequence to be converted,
and the number of wide characters written to \fIdest\fP is returned.
.PP
3. The multibyte string has been completely converted, including the
terminating '\\0' (which has the side effect of bringing back \fI*ps\fP to the
initial state).
In this case \fI*src\fP is set to NULL, and the number of wide
characters written to \fIdest\fP, excluding the terminating L'\\0' character,
is returned.
.PP
If \fIdest\fP is NULL, \fIlen\fP is ignored, and the conversion proceeds as
above, except that the converted wide characters are not written out to memory,
and that no length limit exists.
.PP
In both of the above cases, if \fIps\fP is a NULL pointer, a static anonymous
state only known to the mbsrtowcs function is used instead.
.PP
The programmer must ensure that there is room for at least \fIlen\fP wide
characters at \fIdest\fP.
.SH "RETURN VALUE"
The
.BR mbsrtowcs ()
function returns the number of wide characters that make
up the converted part of the wide-character string, not including the
terminating null wide character.
If an invalid multibyte sequence was
encountered, (size_t)(\-1) is returned, and \fIerrno\fP set to \fBEILSEQ\fP.
.SH "CONFORMING TO"
C99
.SH NOTES
The behavior of
.BR mbsrtowcs ()
depends on the
.B LC_CTYPE
category of the
current locale.
.PP
Passing NULL as \fIps\fP is not multi-thread safe.
.SH "SEE ALSO"
.BR iconv (3),
.BR mbsnrtowcs (3),
.BR mbstowcs (3)