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From: nukuduma@tornado.osk.kubota.co.jp (Kouji Nukuduma)
Subject: Re: Why does ANSI C have offsetof macro?
Organization: Kubota Corp., Osaka, Japan.
Date: Wed, 19 Jan 1994 08:23:20 GMT
Message-ID: <NUKUDUMA.94Jan19172320@tornado.osk.kubota.co.jp>
In-Reply-To: sasayama@otsl.oki.co.jp's message of 19 Jan 94 04:31:11 GMT
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($B3t(B)$B%/%\%?$NE[5W:J$G$9!#30$7$F$?$i$9$_$^$;$s!#(B

In article <SASAYAMA.94Jan19133111@jellybean.otsl.oki.co.jp> writes:

>> ANSI C$B$K$O(Boffsetof$B%^%/%m$,$"$j$^$9$,!$$3$l$O2?$N$?$a$K$"$k$N$G$7$g$&$+!#(B
>>
>> offsetof$B%^%/%m$O(Bstddef.h$B$GDj5A$5$l$k$N$G!$$*$=$i$/(BANSI$B0JA0$K$O$J$+$C$?(B
>> $B$b$N$H;W$o$l$^$9$,!$;d$O$3$N%^%/%m$N;H$$J}$r2r@b$7$F$$$kJ88%$rA4$/CN$j(B
>> $B$^$;$s!#$3$l$O0lBN2?$N$?$a$KH/L@$5$l$?$N$G$7$g$&$+!#(B

#define offsetof(type,member) \
 ((unsigned int)(((char *)(&(((type)NULL)->member))) - ((char *)NULL)))

$B$H$9$l$P!"(BANSI $B0JA0$N=hM}7O$G$bMxMQ$G$-$^$9!#(B

>> $B;d$O$3$N%^%/%m$N;H$$J}$H$7$F2DJQD99=B$BN$N%5%$%:$r7W;;$9$k$3$H$7$+;W$$(B
>> $B$D$+$J$$$N$G$9$,!$$3$l$O$3$N%^%/%mK\Mh$N;H$$J}$J$N$G$7$g$&$+!#$=$l$H$b(B
>> $B$[$+$K@5Ev$J;H$$J}$,$"$k$N$G$7$g$&$+!#(B

$B;d$O(B offsetof $B$O;H$C$?$3$H$,$"$j$^$;$s$,!"A0=R$N%^%/%m$O;H$C$?$3$H$,$"(B
$B$j$^$9!#(B

$BL5O@!"9=B$BN$N@hF,$+$i3:Ev%a%s%P$^$G$N%*%U%;%C%H$rF@$k$?$a$G!"Nc$($P(B
$B4D6-%U%!%$%k$rFI$_9~$s$G!"%f!<%6!<$,:n@.$7$?G$0U$N9=B$BN$KCM$r%;%C%H$9(B
$B$kHFMQ4D6-%U%!%$%kFI$_9~$_4X?t$r:n@.$7$?;~$G$7$?!#(B

$B$3$N$h$&$J>l9g!"4D6-JQ?t$b<+M3$K%+%9%?%^%$%:$G$-$kI,MW$,$"$j!"(B
$B!V!_!_!a!{!{$,$"$l$P!"%a%s%P(BXX$B$K!{!{$rBeF~$9$k!W$C$F$J$3$H$,I,MW$K$J$j(B
$B$^$9$,!"$b$A$m$sHFMQ4X?t$O%a%s%P(BXX$B$J$s$FCN$i$J$$(B($BCN$l$J$$(B)$BLu$G$9!#(B

$B$3$NMM$J>l9g(B offset $B$,$"$l$P!"!V9=B$BN$N@hF,$+$i2?%P%$%HL\$NItJ,$K!"(B
int$B7?$N%a%s%P(BXX$B$,$"$k$h!W$H;XDj$9$k$3$H$,$G$-$^$9!#(B

$B!t=q$$$F$k$&$A$K!"F,$,%0%A%c%0%A%c$K$J$C$F$7$^$C$?!#(B
$B!t$A$c$s$H@bL@$K$J$C$F$$$k$G$7$g$&$+!)(B

$B#X%D!<%k%-%C%H$N%W%m%0%i%_%s%0$G$b!"F1MM$J%^%/%m$r07$&ItJ,$,$"$C$?$H;W(B
$B$$$^$9!#(B
--
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  $BE[5W:J(B $B9(Fs(B  mail:nukuduma@kubota.co.jp            fax:06-949-5053
