Update, since this got attention: I remembered slightly wrong: "b" would need to be declared before "a", not after and you'd access it with "a[3]" not "a[4]". So after this, "b" would be 7: "int b=5; int a[3]; a[3]=7;". Looks like I'm still making the same mistakes.

But still: If you passed the array and referenced it wrong it would change local variables in some remote stack frame.