Default constructor c++

Question

I am trying to understand how default constructor (provided by the compiler if you do not write one) versus your own default constructor works.

So for example I wrot

Answer 1

 A n();

declares a function, named n, that takes no arguments and returns an A.

Since it is a declaration, no code is invoked/executed (especially no constructor).

After that declaration, you might write something like

A myA = n();

This would compile. But it would not link! Because there is no definition of the function n.