That's correct --- the standard doesn't say anything about raw memory. Only pointers to objects defined by C are defined to work; everything else is an implemen

That's correct --- the standard doesn't say anything about raw memory. Only pointers to objects defined by C are defined to work; everything else is an implementation-specific extension (and so, covered under 'undefined behaviour'). I believe that C99 added the ability to losslessly cast from a pointer to a uintptr_t and back again, but, IIRC, the compiler didn't have to support this in C89.