.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
.\" and Copyright 2015 Michael Kerrisk <mtk.manpages@gmail.com>
.\"
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.\" manual page may be incorrect or out-of-date.  The author(s) assume no
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.\" References consulted:
.\"     Linux libc source code
.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
.\"     386BSD man pages
.\" Modified Sun Jul 25 10:41:09 1993 by Rik Faith (faith@cs.unc.edu)
.\"*******************************************************************
.\"
.\" This file was generated with po4a. Translate the source file.
.\"
.\"*******************************************************************
.\"
.\" Japanese Version Copyright (c) 1997 Ueyama Rui
.\"         all rights reserved.
.\" Translated Tue Feb 21 0:49:30 JST 1997
.\"         by Ueyama Rui <ueyama@campusnet.or.jp>
.\"
.TH MEMCPY 3 2017\-09\-15 "" "Linux Programmer's Manual"
.SH 名前
memcpy \- メモリー領域をコピーする。
.SH 書式
.nf
\fB#include <string.h>\fP
.PP
\fBvoid *memcpy(void *\fP\fIdest\fP\fB, const void *\fP\fIsrc\fP\fB, size_t \fP\fIn\fP\fB);\fP
.fi
.SH 説明
\fBmemcpy\fP()  はメモリー領域 \fIsrc\fP の先頭 \fIn\fP バイトを メモリー領域 \fIdest\fP にコピーする。コピー元の領域と
コピー先の領域が重なってはならない。重なっている場合は \fBmemmove\fP(3)  を使うこと。
.SH 返り値
\fBmemcpy\fP()  は \fIdest\fP へのポインターを返す。
.SH 属性
この節で使用されている用語の説明については、 \fBattributes\fP(7) を参照。
.TS
allbox;
lb lb lb
l l l.
インターフェース	属性	値
T{
\fBmemcpy\fP()
T}	Thread safety	MT\-Safe
.TE
.SH 準拠
POSIX.1\-2001, POSIX.1\-2008, C89, C99, SVr4, 4.3BSD.
.SH 注意
.\" glibc commit 6fb8cbcb58a29fff73eb2101b34caa19a7f88eba
.\" From forward copying to backward copying
Failure to observe the requirement that the memory areas do not overlap has
been the source of significant bugs.  (POSIX and the C standards are
explicit that employing \fBmemcpy\fP()  with overlapping areas produces
undefined behavior.)  Most notably, in glibc 2.13 a performance optimization
of \fBmemcpy\fP()  on some platforms (including x86\-64) included changing the
order in which bytes were copied from \fIsrc\fP to \fIdest\fP.
.PP
.\" Adobe Flash player was the highest profile example:
.\"   https://bugzilla.redhat.com/show_bug.cgi?id=638477
.\"   Reported: 2010-09-29 02:35 EDT by JCHuynh
.\"   Bug 638477 - Strange sound on mp3 flash website
.\"
.\"   https://sourceware.org/bugzilla/show_bug.cgi?id=12518
.\"   Bug 12518 - memcpy acts randomly (and differently) with overlapping areas
.\"   Reported:       2011-02-25 02:26 UTC by Linus Torvalds
.\"
.\" glibc commit 0354e355014b7bfda32622e0255399d859862fcd
This change revealed breakages in a number of applications that performed
copying with overlapping areas.  Under the previous implementation, the
order in which the bytes were copied had fortuitously hidden the bug, which
was revealed when the copying order was reversed.  In glibc 2.14, a
versioned symbol was added so that old binaries (i.e., those linked against
glibc versions earlier than 2.14)  employed a \fBmemcpy\fP()  implementation
that safely handles the overlapping buffers case (by providing an "older"
\fBmemcpy\fP()  implementation that was aliased to \fBmemmove\fP(3)).
.SH 関連項目
\fBbcopy\fP(3), \fBbstring\fP(3), \fBmemccpy\fP(3), \fBmemmove\fP(3), \fBmempcpy\fP(3),
\fBstrcpy\fP(3), \fBstrncpy\fP(3), \fBwmemcpy\fP(3)
.SH この文書について
この man ページは Linux \fIman\-pages\fP プロジェクトのリリース 5.10 の一部である。プロジェクトの説明とバグ報告に関する情報は
\%https://www.kernel.org/doc/man\-pages/ に書かれている。