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

No there is not a different constructor.

A n();

is treated as a declaration of function taking no arguments and returning A object. You can see this with this code:

class A
{
public:
    int x;

public:

    A(){ std::cout << "Default constructor called for A\n";}

    A(int x){

        std::cout << "Argument constructor called for A\n";

        this->x = x;

    }
};


int main(int argc, char const *argv[])
{

    A m;
    A p(0);
    A n();
    n.x =3;

    return 0;
}

The error is:

main.cpp:129: error: request for member ‘x’ in ‘n’, which is of non-class type ‘A()’