ARIEL@RELAY.Prime.COM (07/13/90)
A small clarification re "certain Prime computers": The Prime 50 Series does use a non-zero representation for NULL in some languages, particularily PL/I. The C NULL is all 0-bits. Sometimes (in IX mode) 32 of them, other times (V mode, on older machines) 48 bits. If i is an int, and p is a pointer, then (in IX mode): i = (int)p; p = (void *)i; changes the bit pattern. (i.e after these two statements *(int *)&i != *(int *)&p is true if p != NULL) The change is invertable (p ends up with the same value) IF p is actually a valid pointer (including NULL of course) Robert Ullmann