'\" t
.\" Copyright (c) Bruno Haible <haible@clisp.cons.org>
.\"
.\" SPDX-License-Identifier: GPL-2.0-or-later
.\"
.\" 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 wctomb 3 2023-03-30 "Linux man-pages 6.04"
.SH NAME
wctomb \- convert a wide character to a multibyte sequence
.SH LIBRARY
Standard C library
.RI ( libc ", " \-lc )
.SH SYNOPSIS
.nf
.B #include <stdlib.h>
.PP
.BI "int wctomb(char *" s ", wchar_t " wc );
.fi
.SH DESCRIPTION
If
.I s
is not NULL,
the
.BR wctomb ()
function converts the wide character
.I wc
to its multibyte representation and stores it at the beginning of
the character array pointed to by
.IR s .
It updates the shift state, which
is stored in a static anonymous variable
known only to the
.BR wctomb ()
function,
and returns the length of said multibyte representation,
that is, the number of
bytes written at
.IR s .
.PP
The programmer must ensure that there is
room for at least
.B MB_CUR_MAX
bytes at
.IR s .
.PP
If
.I s
is NULL, the
.BR wctomb ()
function
.\" The Dinkumware doc and the Single UNIX specification say this, but
.\" glibc doesn't implement this.
resets the shift state, known only to this function,
to the initial state, and
returns nonzero if the encoding has nontrivial shift state,
or zero if the encoding is stateless.
.SH RETURN VALUE
If
.I s
is not NULL, the
.BR wctomb ()
function
returns the number of bytes
that have been written to the byte array at
.IR s .
If
.I wc
can not be
represented as a multibyte sequence (according
to the current locale), \-1 is returned.
.PP
If
.I s
is NULL, the
.BR wctomb ()
function returns nonzero if the
encoding has nontrivial shift state, or zero if the encoding is stateless.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.ad l
.nh
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.BR wctomb ()
T}	Thread safety	MT-Unsafe race
.TE
.hy
.ad
.sp 1
.SH VERSIONS
The function
.BR wcrtomb (3)
provides
a better interface to the same functionality.
.SH STANDARDS
C11, POSIX.1-2008.
.SH HISTORY
POSIX.1-2001, C99.
.SH NOTES
The behavior of
.BR wctomb ()
depends on the
.B LC_CTYPE
category of the
current locale.
.SH SEE ALSO
.BR MB_CUR_MAX (3),
.BR mblen (3),
.BR mbstowcs (3),
.BR mbtowc (3),
.BR wcrtomb (3),
.BR wcstombs (3)