c define arrays in struct with different sizes

Question

I need to define a struct for two types of objects. Both have exactly the same data structure and perform same tasks (member methods).

The ONLY difference is that the a

Answer 1

Even with a union, the struct will be as big as the largest of the two arrays.

Do one of these:

1. Ignore the overhead of the biggest array size. (Use one array or a union)
2. Create a separate struct for each type.
3. Dynamically allocate the array with malloc.