.\" Copyright (c) 2002 Tim J. Robbins
.\" All rights reserved.
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.\" $FreeBSD$
.Dd August 16, 2002
.Dt MBRLEN 3
.Os
.Sh NAME
.Nm mbrlen
.Nd "get number of bytes in a character (restartable)"
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In wchar.h
.Ft size_t
.Fn mbrlen "const char *restrict s" "size_t n" "mbstate_t *restrict ps"
.Sh DESCRIPTION
The
.Fn mbrlen
function determines the the number of bytes constituting the
multibyte character sequence pointer to by
.Fa s .
.Pp
It is equivalent to:
.Pp
.Dl "mbrtowc(NULL, s, n, ps);"
.Pp
Except that when
.Fa ps
is a NULL pointer,
.Fn mbrlen
uses its own static, internal
.Ft mbstate_t
object to keep track of shift state.
.Sh RETURN VALUES
The
.Fn mbrlen
functions returns:
.Bl -tag -width indent
.It 0
The first
.Fa n
or fewer bytes of
.Fa s
represent the null wide character (L'\e0').
.It >0
The first
.Fa n
or fewer bytes of
.Fa s
represent a valid character,
.Fn mbrtowc
returns the length (in bytes) of the multibyte sequence.
.It Xo
.No ( Ns
.Ft size_t Ns
.No ) Ns \&-2
.Xc
The first
.Fa n
bytes of
.Fa s
are an incomplete multibyte sequence.
.It Xo
.No ( Ns
.Ft size_t Ns
.No ) Ns \&-1
.Xc
The byte sequence pointed to by
.Fa s
is an invalid multibyte sequence.
.El
.Sh ERRORS
The
.Fn mbrlen
function will fail if:
.Bl -tag -width Er
.\".It Bq Er EINVAL
.\"Invalid argument.
.It Bq Er EILSEQ
An invalid multibyte sequence was detected.
.El
.Sh SEE ALSO
.Xr mblen 3 ,
.Xr mbrtowc 3
.Sh STANDARDS
The
.Fn mbrlen
function conforms to
.St -isoC-99 .
.Sh BUGS
The current implementation does not support shift states.