.\" Copyright (c) 2002-2004 Tim J. Robbins. All rights reserved.
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.\" From @(#)multibyte.3	8.1 (Berkeley) 6/4/93
.\" From FreeBSD: src/lib/libc/locale/multibyte.3,v 1.22 2003/11/08 03:23:11 tjr Exp
.\" $FreeBSD: head/lib/libc/locale/mblen.3 165903 2007-01-09 00:28:16Z imp $
.\"
.Dd December 26, 2013
.Dt MBLEN 3
.Os
.Sh NAME
.Nm mblen ,
.Nm mblen_l
.Nd get number of bytes in a character
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In stdlib.h
.Ft int
.Fn mblen "const char *mbchar" "size_t nbytes"
.In xlocale.h
.Ft int
.Fn mblen_l "const char *mbchar" "size_t nbytes" "locale_t locale"
.Sh DESCRIPTION
The
.Fn mblen
and
.Fn mblen_l
functions compute the length in bytes
of a multibyte character
.Fa mbchar
according to a conversion state.
Up to
.Fa nbytes
bytes are examined.
.Pp
A call with a null
.Fa mbchar
pointer returns nonzero if the locale requires shift states,
zero otherwise;
if shift states are required, the shift state is reset to the initial state.
.Pp
The
.Fn mblen_l
function takes an explicit
.Fa locale
argument, whereas the
.Fn mblen
function uses the current global or per-thread locale.
.Sh RETURN VALUES
If
.Fa mbchar
is
.Dv NULL ,
the
.Fn mblen
and
.Fn mblen_l
functions return nonzero if shift states are supported,
zero otherwise.
.Pp
Otherwise, if
.Fa mbchar
is not a null pointer,
.Fn mblen
and
.Fn mblen_l
either return 0 if
.Fa mbchar
represents the null wide character, or return
the number of bytes processed in
.Fa mbchar ,
or return \-1 if no multibyte character
could be recognized or converted.
In this case,
.Fn mblen Ns 's
and
.Fn mblen_l Ns 's
internal conversion states are undefined.
.Sh ERRORS
The
.Fn mblen
and
.Fn mblen_l
functions will fail if:
.Bl -tag -width Er
.It Bq Er EILSEQ
An invalid multibyte sequence was detected.
.It Bq Er EINVAL
The internal conversion state is not valid.
.El
.Sh SEE ALSO
.Xr mbrlen 3 ,
.Xr mbtowc 3 ,
.Xr multibyte 3 ,
.Xr xlocale 3
.Sh STANDARDS
The
.Fn mblen
function conforms to
.St -isoC-99 .