How can you find the size of a datatype without creating a variable or pointer, or using sizeof of the datatype?

Question

The question shown below is an interview question:

Q) You are given/have a datatype, say X in C.

The requirement is to get the size of the datatype, without decl

Answer 1

You can typecast 0 (or any arbitrary value) to type datatype X* to find the size of the datatype, just like the below example:

    #include 

    struct node{
        char c;
        int i;
    };

    int main()
    {
        printf("Sizeof node is: %d\n", ((char *)((struct node *)0 + 1) - (char *)((struct node *)0)));   
// substract 2 consecutive locations starting from 0 that point to type node, 
//typecast these values to char * to give the value in number of bytes.
        return 0;
    }