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.\" Chris Torek and the American National Standards Committee X3,
.\" on Information Processing Systems.
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.\"     @(#)fread.3	6.6 (Berkeley) 6/29/91
.\"
.\" Converted for Linux, Mon Nov 29 15:37:33 1993, faith@cs.unc.edu
.\" Sun Feb 19 21:26:54 1995 by faith, return values
.\" Modified Thu Apr 20 20:43:53 1995 by Jim Van Zandt <jrv@vanzandt.mv.com>
.\" Modified Fri May 17 10:21:51 1996 by Martin Schulze <joey@infodrom.north.de>
.\"
.\" Japanese Version Copyright (c) 1997 YOSHINO Takashi
.\"       all rights reserved.
.\" Translated Tue Jan 21 21:57:33 JST 1997
.\"       by YOSHINO Takashi <yoshino@civil.jcn.nihon-u.ac.jp>
.\" Updated & Modified Mon Mar 1 1999
.\"       by NAKANO Takeo <nakano@apm.seikei.ac.jp>
.\" Updated Sat Nov  3 JST 2001 by Kentaro Shirakata <argrath@ub32.org>
.\"
.TH FREAD 3  1996-05-17 "GNU" "Linux Programmer's Manual"
.SH 名前
fread, fwrite \- バイナリストリームの入出力
.SH 書式
.nf
.B #include <stdio.h>
.sp
.BI "size_t fread(void *" ptr ", size_t " size ", size_t " nmemb \
", FILE *" stream );
.sp
.BI "size_t fwrite(const void *" ptr ", size_t " size ", size_t " nmemb ,
.BI "              FILE *" stream );
.fi
.SH 説明
.BR fread ()
関数は
.I stream
ポインタで指定されたストリームから
.I nmemb
個のデータを読み込み、
.I ptr
で与えられた場所に格納する。
個々のデータは
.I size
バイトの長さを持つ。
.PP
.BR fwrite ()
関数は
.I ptr
で指定された場所から得た
.I nmemb
個のデータを、
.I stream
ポインタで指定されたストリームに書き込む。
個々のデータは
.I size
バイトの長さを持つ。
.PP
.\"O For nonlocking counterparts, see
.\"O .BR unlocked_stdio (3).
これらの処理を停止せずに行いたいときは、
.BR unlocked_stdio (3)
を参照のこと。
.SH 返り値
.BR fread ()
と
.BR fwrite ()
は読み書きに成功した要素の個数を返す。
エラーが生じた場合や、end-of-file(ファイルの最後)に達した場合、
返り値は指定した個数よりも小さい値(またはゼロ)となる。
.PP
.BR fread ()
は end-of-file とエラーを区別しないので、
どちらが生じたかを判断するためには、
呼び出し側で
.BR feof (3)
と
.BR ferror (3)
とを使用しなければならない。
.SH 準拠
C89, POSIX.1-2001.
.SH 関連項目
.BR read (2),
.BR write (2),
.BR feof (3),
.BR ferror (3),
.BR unlocked_stdio (3)