Can a pointer point to an address after 4GB?

Question

If we compile and execute the code below:

int *p;
printf("%d\n", (int)sizeof(p));

it seems that the size of a pointer to whatever the type is 4 bytes, which means 32 bit, so 2³² adresses are possible to store in a pointer. Since every address is associated to 1 byte, 2³² bytes give 4 GB.

So, how can a pointer point to the address after 4 GB of memory? And how can a program use more than 4 GB of memory?

Answer 1

By principle, if you can't represent an address which goes over 2^X-1 then you can't address more than 2^X bytes of memory.

This is true for x86 even if some workarounds have been implemented and used (like PAE) that allows to have more physical memory even if with limits imposed by the fact that these are more hacks than real solutions to the problem.

With a 64 bit architecture the standard size of a pointer is doubled, so you don't have to worry anymore.

Mind that, in any case, virtual memory translates addresses from the process space to the physical space so it's easy to see that a hardware could support more memory even if the maximum addressable memory from the process point of view is still limited by the size of a pointer.