Java $B$NEP>l$K$h$C$F(B GC $B$b?M8}$Kg:_U$7$F$-$^$7$?!#(B $B$7$+$7!"B?$/$N?M$,$^$@(B $B@lMQ$N%W%m%0%i%`8@8l$H%$%s%?%W%j%?(B $B%i%s%?%$%`$,(B $B$J$1$l$P(B GC $B$O;H$($J$$$H9M$($F$$$^$9!#(B Boehm GC $B%i%$%V%i%j$O!"(B $B=>Mh$N(B C $B8@8l$N(B malloc $B4X?t$r(B GC_malloc $B4X?t$XCV$-49$((B free $B4X?t$r
Boehm GC $B$O!"(B $B$[$H$s$I$N(B UNIX $B7O(B OS$B!"(BWin9x $B7O!"(BNT$B7O!"(BOS/2$B!"(BAmiga OS$B!"(B Mac OS 8$B!&(B9$B$KBP1~$7$F$$$^$9!#(B
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Boehm GC $B$N%Z!<%8(B "A garbage collector for C and C++"$B$O!"(B $B8=:_(B $B$3$3(B $B$K$"$j$^$9!#(B
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GC $B$K$D$$$F(B $B$b$&(B1$BEY$*$5$i$$$r$7$^$9!#(BC/C++ $B$G$O(B malloc ($B$^$?$O(B new)$B$K$h$C$FF0E*$K3NJ]$5$l$?%a%b%j$O!"(B free ($B$^$?$O(B delete) $B$K$h$C$F(B $BL@<(E*$K2rJ|$9$kI,MW$,$"$j$^$9!#(B
$B$3$N$h$&$JL@<(E*$J%a%b%j3NJ]$K$O!"(B $B%P%0$r@8$_=P$9860x$H$J$k(B $B$$$m$$$mLdBj$,@8$8$^$9!#(B
- $B%a%b%j%j!<%/(B(memory leak)
- $B$9$G$KITMQ$K$J$C$?%a%b%j$r(B
$B2rJ|$7K:$l$?$^$^!"(B
$B$=$NNN0h$X$N;2>H(B($B%]%$%s%?(B)$B$r<:$C$?>uBV!#(B
C/C++ $B$G$O!"(B
1$BEY(B $B;2>H(B($B%]%$%s%?(B)$B$r<:$C$F$7$^$C$?(B
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{
$B$3$N>l9g!"(B $B%W%m%0%i%`$,=*N;$9$k$^$G2s<}$G$-$J$$(B $B%a%b%jNN0h$,(B $B%W%m%;%9Cf$K;D$k$3$H$K$J$j$^$9!#(B $B$3$l$r%a%b%j%j!<%/$H8F$S$^$9!#(B $B%a%b%j%j!<%/$,@Q$b$C$F9T$/$H!"(B $B;HMQ2DG=$J%a%b%j$,A}$($F$f$-!"(B $B%W%m%0%i%`$rDd;_$;$6$k$($J$/$J$j$^$9!#(B
{
char* p = (char*)malloc( SIZE ); /* (1) */
}
/* $BJQ?t(B p $B$,%9%3!<%W$N30$K=P$k$H!"(B(1) $B$K$h$C$F3NJ]$5$l$?(B
$B%a%b%jNN0h$O2rJ|ITG=(B */
}
- $B%@%s%0%j%s%0%]%$%s%?(B(dangling pointer)
- $B%]%$%s%?$,IT@5$J%a%b%jNN0h$r;X$7$F$$$k>uBV$r(B
$B%@%s%0%j%s%0%]%$%s%?$H8F$S$^$9!#(B
$BFC$K(B C / C++ $B$G$O%]%$%s%?$KG$0U$NCM$rBeF~$G$-$k$N$G!"(B $BMM!9$J%?%$%W$N%@%s%0%j%s%0%]%$%s%?$,H/@8$7$^$9!#(Bvoid foo(char** p) {
$B%@%s%0%j%s%0%]%$%s%?$NCf$G(B $B:G$bH/8+$,8+$D$1?I$$$N$,!"(B $BK\Mh(B $B@5>o$J%*%V%8%'%/%H$r;X$7$F$$$?%]%$%s%?$,!"(B $B;2>H$7$F$$$k%*%V%8%'%/%H$,2rJ|$5$l$?$?$a$K(B $B%@%s%0%j%s%0%]%$%s%?$r;X$7$F$7$^$&%Q%?!<%s$G$9!#(B
char c;
*p = &c;
}
char* p = NULL;
foo(&p);
/* p $B$OIT@5$J%a%b%j%"%I%l%9$r;X$7$F$$$k(B */char* p = (char*) malloc(SIZE);
$B2rJ|$5$l$?NN0h$,!"(B $Bl9g!"(B $BIT@5$J=q$-JQ$($r9T$C$F$7$^$$$^$9!#(B
free(p);
char* q = (char*) malloc(SIZE);
/* p $B$OIT@5$J%a%b%j%"%I%l%9$r;X$7$F$$$k(B */
/* $B$b$7$+$9$k$H(B p == q $B$G!"(Bp $B$r=q$-D>$9$H(B q $B$NFbMF$,JQ$o$k$+$b(B */
$B%$%s%9%H!<%k(B
$B$^$:!"(B $B%=!<%9%3!<%I$,I,MW$G$9!#(B $B$3$3$+$i(B $B%=!<%9%3!<%I$r;}$C$F$-$^$7$g$&!#(B $B8=:_$N:G?7%P!<%8%g%s$O(B 6.1$B!"%U%!%$%kL>$O(B gc6.1.tar.gz $B$G$9!#(B $B$3$3$G$O!"(B UNIX $B7O(B OS $B$G$N%$%s%9%H!<%kJ}K!$K$D$$$F@bL@$7$^$9!#(B$B%i%$%V%i%j$r;H$&$?$a$KI,MW$J(B include $B%U%!%$%k$O%$%s%9%H!<%k$5$l$F$$$^$;$s!#(B gc6.1/include $B$N2<$N%U%!%$%k$r!"E,Ev$J%G%#%l%/%H%j$K%3%T!<$7$F$*$-$^$7$g$&!#(B> tar xzvf gc6.1.tar.gz
> cd gc6.1/ > ./configure > make > make check > su # make install
LD_LIBRARY_PATH $B$K%i%$%V%i%j$r%$%s%9%H!<%k@h$N%G%#%l%/%H%j$rF~$l$^$9!#(B (Linux $B$J$i(B ld.so.conf $B$K%$%s%9%H!<%k@h$N%G%#%l%/%H%j$rDI2C$7$F!"(B ldconfig $B%3%^%s%I$r# cp -r include /usr/local/include/gc
$B99?7MzNr!'(B
2004.01.08 dangling pointer $B$NNc$,4V0c$C$F$$$k$H$N;XE&$r$$$?$@$$$?$N$G=$@5!#(B
$BLa$k(B
Written by NAKAMURA Minoru, Email: nminoru atmark nminoru dot jp, Twitter:@nminoru_jp