Access struct members as if they are a single array?

Question

I have two structures, with values that should compute a pondered average, like this simplified version:

typedef struct
{
  int v_move, v_read, v_suck, v_flu         


        

Answer 1

Writing the question came to my mind... Can a union do the job? Is there another clever way to automatize the task of adding another member?

Yes, a union can certainly do the job:

union
{
  values v;    /* As defined by OP */
  int array[6];
} u;

You can use a pointer to u.values in your API, and work with u.array in your code.

Personally, I think that all the other answers break the rule of least surprise. When I see a plain struct definition, I assume that the structure will be access using normal access methods. With a union, it's clear that the application will access it in special ways, which prompts me to pay extra attention to the code.