Virtual Memory or Physical Memory

Question

Suppose we write a program in C and print the address of one of the variables declared in the program, is the address that gets printed on the screen the virtual address or the

Answer 1

In most typical cases (Windows, Linux, etc.) it'll be a virtual address.

In the typical cases like Linux and Windows, both virtual addresses and physical addresses are normally 32 bits, so having numbers in the same range becomes inevitable. It is possible to allocate more than 4 gigabytes of memory, and when/if you do so, you end up with addresses larger than 32 bits--but unless you take special steps to do that, a 32-bit address is what you'll get by default.

When you do use more than 4 GB of memory under a 32-bit OS, you're normally doing so via some special API, such as Windows' Address Windowing Extensions. Using these, you get access to more than 4 GB of RAM, but it's not what's going to happen by default with code that's even close to portable.

Some (versions of some) operating systems also use Intel's Physical Address Extensions (PAE) to give the system as a whole access to more than 4 GB of RAM, but even when these are in use, any single process running on the system is still limited to addressing 4 GB (i.e., with PAE, you can have a limit of 4 GB per process, whereas older systems had a limit of 4 GB total, divided as needed between the processes).