C++ Question about default constructor

Question

Hi, I have a question.

What does it mean to call a class like this:

class Example
{
 public: 
  Example(void);
  ~Example(void);
}

int main(void)
{
 Example ex(); // <<<<<< what is it called to call it like this?

 return(0);
}

Like it appears that it isn't calling the default constructor in that case. Can someone give a reason why that would be bad?

Thanks for all answers.

Answer 1

Does it even compile? Anyway, see this related topic.

Answer 2

Currently you are trying to call the default constructor like so.

Example ex();

This is not actually calling the default constructor. Instead you are defining a function prototype with return type Example and taking no parameters. In order to call the default constructor, omit the ()'s

Example ex;

Answer 3

This declares a function prototype for a function named ex, returning an Example! You are not declaring and initializing a variable here.

Answer 4

As has been noted Example ex(); declares a function prototype. Not what anyone would expect. This C++ wart will be fixed by the new C++0x standard. In the future the preferred syntax will be Example ex{};. The new uniform construction has many other nice features, see more here.