Is struct packing deterministic?

Question

For example, say I have two equivalent structs a and b in different projects:

typedef struct _a
{
    int a;
    double b;
    char         


        

Answer 1

will they have identical padding between variables?

In practice, they mostly like to have the same memory layout.

In theory, since the standard doesn't say much on how padding should be employed on objects, you can't really assume anything on the padding between the elements.

Also, I can't see even why would you want to know/assume something about the padding between the members of a struct. simply write standard, compliant C code and you'll be fine.