Struct's contribution to type size

Question

I am wondering why the following two types

struct {
    double re[2];
};

and

double re[2];

have the same size in C? Doesn't struct add a bit of size overhead?

Answer 1

No, it just merely composes all the elements into one higher-level element whose size is merely the individual elements' sizes added up (plus some padding depending on alignment rules, but that's out of the scope of this question).