用名称中的作用域解析运算符声明一个指针

Question

I'm trying to make sence of this tutorial on doubly linked lists. http://www.dreamincode.net/forums/topic/53161-how-to-create-a-basic-double-linked-list/

I can't understand this part

  element* list::FirstEl = NULL;    //This initialises the static element* 'FirstEl' to  NULL  
  element* list::LastEl = NULL;     //This initialises the static element* 'LastEl' to  

I would say this code creates a pointer of type element with the name "list::FirstEl" and sets it to null, but the scope resolution operator makes me think there is something I still havn't covered in C++ yet.

What's going on here?

Answer 1

That's a static class member initializtion.

class list
{
    static element* FirstEl;
    static element* LastEl;
};

what you have there is the initialization of the members.

The name of the variables are FirstEl and LastEl , but they are part of the class, that's why you have to qualify their names when you define them.

Just like you'd qualify method names when you'd define them.