Question

I have the following files:

H file

class myclass
{
   static int variable;

   // constructor
   myclass();
}

Cpp file

// initialize this variable
int myclass::variable = 0;

myclass::myclass()
{
   // I use here the static variable
}

My question is: when is the static variable going to be initialized? First or after the constructor?

What if I put the

int myclass::variable = 0;

line after the class constructor definition? Will it still be initialized before a class’ object is instantiated?

Answer 1

A static like this will be initialised when the application starts up, which I assume will be way before you instantiate “myclass”.

Basically it doesn’t matter where you define it due to this.

However, if you create a global copy of “myclass” then I believe you can get into issues. It would be perfectly legal to put the definition before the variable initialisation e.g.

myclass globalInstance;
int myclass::variable = 0;

In the above case I’m pretty sure that myclass’s constructor will be called before variable is initialised. In such a case it would be best to define myclass after variable.

Edit: See http://www.parashift.com/c++-faq/static-init-order.html