What does casting a pointer difference to “int*” mean?

Question

ptr3 = (int *) (ptr2 – ptr1)

ptr2 - ptr1 gives the difference between the subscripts. Casting ptr2 - ptr1 to an integer confuses me since it is already an integer. Why do that? EDIT:- ptr1, ptr2,ptr3 are all pointers

Answer 1

Pointer subtraction yields the result of type ptrdiff_t .

Quoting C11 , chapter §6.5.6/P9

When two pointers are subtracted, both shall point to elements of the same array object, or one past the last element of the array object; the result is the difference of the subscripts of the two array elements. The size of the result is implementation-defined, and its type (a signed integer type) is ptrdiff_t defined in the <stddef.h> header [...]

Here, the attempt is to cast that to an int * , which does not appear to be proper.