size of a datatype without using sizeof

Question

I have a data type, say X, and I want to know its size without declaring a variable or pointer of that type and of course without using sizeof oper

Answer 1

One simple way of doing this would be using arrays. Now, we know for the fact that in arrays elements of the same datatype are stored in a contiguous block of memory. So, by exploiting this fact I came up with following:

#include 
using namespace std;

int main()
{
    int arr[2];
    int* ptr = &arr[0];
    int* ptr1 = &arr[1];
    cout <<(size_t)ptr1-(size_t)ptr;
}

Hope this helps.