Re: array size 1 ? All headers

[Eric Bambach <eric@cisu.net>]

On Tuesday 20 July 2004 09:57 pm, you wrote:

Sorry Luiz, meant to send this to the list. Doh.....

>  compiles and works here! but to be honest, I don't why. I can prove it is
> an odd case, becase this also works (here):
>
>  char tst[1];
>  tst[0]='g';
>  tst[1]='r';
>  tst[2]='z';
>
>  printf("%c %c %c\n", tst[0], tst[1], tst[2]);
>
> PS: GCC compiled.


I think small overflows like this will work because arrays are allocated in 
multiples of the word size for the artitecture. So char 
ar[1];
gets 4 bytes as does char ar[2], char ar[3] and char ar[4].
char ar[5] will get 8 bytes. So  with ar[1] and ar[5] you can stuff up to 3 
more charaters until you overwrite critical parts of the stack. Its not an 
error per se, because the space is given to the array, but its a horrible 
thing to do in practice.

Someone correct me if I wrong, im typing this for the sake of teaching and 
learning myself.
-- 
-EB