[clarry]

Pointer arithmetic works element-wise, not byte-wise.

So if p is a pointer, then p+1 refers to the next element after p, regardless of the size of the pointee. And so (p+1) - p is 1, again regardless of the size of the pointee.

In this case, &arr is a pointer to array, and &arr + 1 would point to the next array following the first one. But we wanted to calculate the number of elements in the array, not the fact that we have one array. So we dereference the pointer, thus getting an array type, which in turns "decays" to a pointer to the first element of the array, which has the right type for counting the elements using pointer arithmetic.

[Nimitz14]

Thank you.