Can wrapping a type in a struct cause additional padding? [duplicate]

Question

Possible Duplicate:
Size of struct with a single element

Given any type A and the following struct:

struct S
{
    A a;
};

Are there any cases where sizeof(S) is greater than sizeof(A)?

For example, can sizeof(std::array<T, n>) be greater than sizeof(T[n])?

Answer 1

Being able to use A inside of S means that the compiler already has knowledge of the structure of A and has already added padding bytes to it. I see no reason for it to add further padding to S, as it already is aligned.