Hi Sven.
Yes I was doing the out of bound error on purpose, I was making sure it
segfaulted, but this forever looping thing was not what I was expecting.
The i loopcounter variable should not be affected by a[i] = 1 (which
doesn't happen in a[i] = 11) but it seems to reset itself! This is very
strange.
It would be brilliant if someone could explain this totally different
behavior depending on using a[i] = 1 (forever loop) or a[i] = 11
(segfaults after 1531 loops) in the body of the for-loop.
Thanks very much.
Petur
Sven Eschenberg wrote:
Hi Petur,
This might look strange, but did you realize you are creating a buffer
overflow (out of bound error) and thus I would expect a completely
undefined behavior ... segfaulting really makes sense ... if you ask
me ...
Regards
-Sven
Petur Thors wrote:
Hi
Please correct me if I'm totally lost here , but compiling this
program (a.c) with gcc -Wall -pedantic -o a a.c :
#include <stdio.h>
int main(int argc,char **argv)
{
int i;
int a[10];
for(i = 0; i < 2000; i++) {
printf("a[%d] is %d\n",i,a[i]);
a[i] = 1;
}
return 0;
}
and running it i get :
a[0] is 0
a[1] is 0
a[2] is -2146329632
a[3] is 51
a[4] is 4195584
a[5] is 0
a[6] is 4195312
a[7] is 0
a[8] is -4327808
a[9] is 32767
a[10] is 0
a[11] is 11
a[2] is 1
a[3] is 1
a[4] is 1
a[5] is 1
a[6] is 1
a[7] is 1
a[8] is 1
a[9] is 1
a[10] is 1
a[11] is 11
a[2] is 1
a[3] is 1
a[4] is 1
a[5] is 1
a[6] is 1
a[7] is 1
....
looping forever and ever........
But when I change a[i] = 1 to a[i] = 11 (in the for loop) it
segfaults at i = 1532.
Please forgive me if I'm totally missing something obvious here but
can this be correct ?
gcc specs:
Using built-in specs.
Target: x86_64-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man
--infodir=/usr/share/info --enable-shared --enable-threads=posix
--enable-checking=release --with-system-zlib --enable-__cxa_atexit
--disable-libunwind-exceptions --enable-libgcj-multifile
--enable-languages=c,c++,objc,java,f95,ada --enable-java-awt=gtk
--with-java-home=/usr/lib/jvm/java-1.4.2-gcj-1.4.2.0/jre
--host=x86_64-redhat-linux
Thread model: posix
gcc version 4.0.2 20051125 (Red Hat 4.0.2-8)
Updated Fedora core 4
Thanks in advance and best regards
Petur
