size of pointers and architecture

Question

By conducting a basic test by running a simple C++ program on a normal desktop PC it seems plausible to suppose that sizes of pointers of any type (including pointers to fun

Answer 1

Historically, on microcomputers and microcontrollers, pointers were often wider than general-purpose registers so that the CPU could address enough memory and still fit within the transistor budget. Most 8-bit CPUs (such as the 8080, Z80 or 6502) had 16-bit addresses.

Today, a mismatch is more likely to be because an app doesn’t need multiple gigabytes of data, so saving four bytes of memory on every pointer is a win.

Both C and C++ provide separate size_t, uintptr_t and off_t types, representing the largest possible object size (which might be smaller than the size of a pointer if the memory model is not flat), an integral type wide enough to hold a pointer, and a file offset (often wider than the largest object allowed in memory), respectively. A size_t (unsigned) or ptrdiff_t (signed) is the most portable way to get the native word size. Additionally, POSIX guarantees that the system compiler has some flag that means a long can hold any of these, but you cannot always assume so.