Question

Suppose I have two pointers to type T:

T* first = ...// whatever
T* second = ... //whatever else

Can I be sure that the distance between those two pointers can never exceed:

((size_t)(-1))/sizeof(T)?

Answer 1

You can only compute the distance between two pointers (subtract one pointer from another) if both pointers point to elements in the same array, or to one-past-the-end of the same array.

If the two pointers meet that constraint, then yes, the absolute value of the difference between the two pointers cannot exceed ((size_t)(-1)) / sizeof(T) because size_t must be wide enough to represent the size of any object in bytes.

If the two pointers do not meet that constraint, then there’s no guarantee at all.