C - Find the size of structure

Question

I was asked this as interview question. Couldn\'t answer.

Write a C program to find size of structure without using the sizeof operator.

Answer 1

Here is another approach.... no need to create any instance of structure.

struct  XYZ{
    int x;
    float y;
    char z;
};

int main(){
    int sz = (int) (((struct XYZ *)0) + 1);
    printf("%d",sz);
    return 0;
}

How does it work?

((struct XYZ *)0) + 1 = zero + size of structure
                      = size of structure