.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>

.\"

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.\" modify it under the terms of the GNU General Public License as

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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  2017-09-15 "GNU" "Linux Programmer's Manual"

.SH NAME

mbsrtowcs \- convert a multibyte string to a wide-character string

.SH SYNOPSIS

.nf

.B #include <wchar.h>

.PP

.BI "size_t mbsrtowcs(wchar_t *" dest ", const char **" src ,

.BI "                  size_t " len ", mbstate_t *" ps );

.fi

.SH DESCRIPTION

If

.I dest

is not NULL, the

.BR mbsrtowcs ()

function converts the

multibyte string

.I *src

to a wide-character string starting at

.IR dest .

At most

.I len

wide characters are written to

.IR dest .

The shift state

.I *ps

is updated.

The conversion is effectively performed by repeatedly

calling

.I "mbrtowc(dest, *src, n, ps)"

where

.I n

is some

positive number, as long as this call succeeds, and then incrementing

.I dest

by one and

.I *src

by the number of bytes consumed.

The conversion can stop for three reasons:

.IP 1. 3

An invalid multibyte sequence has been encountered.

In this case,

.I *src

is left pointing to the invalid multibyte sequence,

.I (size_t)\ \-1

is returned,

and

.I errno

is set to

.BR EILSEQ .

.IP 2.

.I len

non-L\(aq\\0\(aq wide characters have been stored at

.IR dest .

In this case,

.I *src

is left pointing to the next

multibyte sequence to be converted,

and the number of wide characters written to

.I dest

is returned.

.IP 3.

The multibyte string has been completely converted, including the

terminating null wide character (\(aq\\0\(aq), which has the side

effect of bringing back

.I *ps

to the

initial state.

In this case,

.I *src

is set to NULL, and the number of wide

characters written to

.IR dest ,

excluding the terminating null wide character, is returned.

.PP

If

.IR dest

is NULL,

.I len

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

.I ps

is NULL, a static anonymous

state known only to the

.BR mbsrtowcs ()

function is used instead.

.PP

The programmer must ensure that there is room for at least

.I len

wide

characters at

.IR dest .

.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,

.I (size_t)\ \-1

is returned, and

.I errno

set to

.BR EILSEQ .

.SH ATTRIBUTES

For an explanation of the terms used in this section, see

.BR attributes (7).

.TS

allbox;

lb lb lbw28

l l l.

Interface	Attribute	Value

T{

.BR mbsrtowcs ()

T}	Thread safety	MT-Unsafe race:mbsrtowcs/!ps

.TE

.sp 1

.SH CONFORMING TO

POSIX.1-2001, POSIX.1-2008, C99.

.SH NOTES

The behavior of

.BR mbsrtowcs ()

depends on the

.B LC_CTYPE

category of the

current locale.

.PP

Passing NULL as

.I ps

is not multithread safe.

.SH SEE ALSO

.BR iconv (3),

.BR mbrtowc (3),

.BR mbsinit (3),

.BR mbsnrtowcs (3),

.BR mbstowcs (3)

.SH COLOPHON

This page is part of release 4.15 of the Linux

.I man-pages

project.

A description of the project,

information about reporting bugs,

and the latest version of this page,

can be found at

\%https://www.kernel.org/doc/man\-pages/.