jack wrote:
>
> the following code can be run and can generate result:
> a[9]=10;
> what happend there?
> int main()
> {
> double *a= new double[10];
> for(int i=0;i<10;i++){
> a[i]=i+1;
> }
> delete [] a;
> cout << a[9] << endl;
> return 0;
> }
You freed the memory, and thereby made it available to the
system for other use. Unfortunately, nothing else in the
system used it, so you got the 10. I say "unfortunately",
because next time you might not get the 10. This is a
common kind of error that has lead to much unreliable
software. To prevent the problem, I always follow
a delete by clearing the pointer:
delete [] a;
a = 0;
Your cout will then result in an immediate, and obvious
crash, which can then be debugged.
Mike.
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