.\" Copyright (c) 1990, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" Chris Torek.
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\"
.\"     @(#)ffs.3	8.2 (Berkeley) 4/19/94
.\" %FreeBSD: src/lib/libc/string/ffs.3,v 1.3.2.2 2001/12/14 18:33:59 ru Exp %
.\" $FreeBSD$
.\"
.Dd April 19, 1994
.Dt FFS 3
.Os
.Sh 名称
.Nm ffs
.Nd ビット列に設定された、最初のビットの検索
.Sh ライブラリ
.Lb libc
.Sh 書式
.In string.h
.Ft int
.Fn ffs "int value"
.Sh 解説
.Fn ffs
関数は、
.Fa value
に設定された最初のビットを検索し、そのビットのインデックスを戻します。
ビットには、最も右のビットを 1 として番号が振られます。
戻り値が 0 である場合は、引数が 0 であったことを表します。
.Sh 関連項目
.Xr bitstring 3
.Sh 歴史
.Fn ffs
関数は、
.Bx 4.3
で登場しました。