C++ - Allocating memory on heap using "new"

Question

If I have the following statement:

int *x = new int;

In this case, I have allocated memory on the heap dynamically. In other words, I now have a reserved memory address for an int object.

Say after that that I made the following:

delete x;

Which means that I freed up the memory address on the heap.

Say after that I did the following again:

int *x = new int;

Will x point to the same old memory address it pointed to at the heap before it was deleted?

What if I did this before delete:

x = NULL;

And, then did this:

int *x = new int;

Will x point to a a memory address on the heap other than the old one?

Thanks.

Answer 1

In the first case, you might get the same block of memory again, but there's no certainty of it.

In the second case, since you haven't freed the memory, there's a near-certainty that you'll get a different block of memory at a different address. There are garbage collectors of C++. If you used one of these, it's conceivable that the garbage collector would run between the time you NULLed out the pointer (so you no longer had access to the previously-allocated memory block) and asking for an allocation again. In such a case, you could get the same memory block again. Of course, without a garbage collector, you're just leaking memory, so you don't way to do this in any case.