What is the difference between int a() and int a=int()?

Question

C++ / C#

I know it sounds silly and I wouldn't be asking if I hadn't experimented in the console

int first (); //  first == 1
int two = int (); // two == 0

But why is that?
For non-primitive types AnyType anyObject (), what AnyType anyObject = AnyType ()is a constructor call, but with primitives?

Answer 1

Now print typeid(first).name() to the screen and be surprised.
The first line is the declaration of the function first without parameters and returning an int. The function name is converted to a pointer, the pointer is converted to bool(true) which is converted to int(1).

Answer 2

implicit type casting or how to shoot yourself in the foot in C and C++