Thread: staitc class

So here is the problem i want to create a class that would be something like this :

Code:

class something
{
private:
  static int i;

public:
  static void operate()
  {
    // do something
  }
}

and there would be only one instance which you would acsses via :: operator. So there is only one of this class in whole project.
Is there a better way to declare a class than write static in front of everything?

what does

Code:

static class
{
...
}something;

mean?

I could make the constructor private, but i still need to create an instance of class...
I just want to create a class that stands for it's own, and that you can't make others, is this possible ?

http://www.google.com/search?q=singleton+class+C%2B%2B

Can you explain what a singleton class is ?
And can you acsses it via :: ?

Have you clicked at least one link?
http://www.codeproject.com/gen/design/singleton.asp

What is a Singleton Class?
Sometimes, you may want to have only one object for a given class and this object should be easily accessible. For example, an Application should have only one Application object and the Job schedulers should share a single Job Queue object. A global variable may provide easy access, but using a global variable will not stop the user from creating more than one object and moreover it is discouraged in Object Oriented Programming. In the above example, the Application class should not allow the user to create more than one object of it and the Job Queue class should ensure that a single Job Queue object is shared by all the Job schedulers. Application and Job Queue classes are called Singleton classes. So, what is a Singleton class ? A class that assures a maximum of ONE object of its type at a given time and provides a global access point to this object is a Singleton class.

You can declare your data members as static. No instances of your class need to be created.

Read about static data members

Originally Posted by Laserve

This is one way to do it

Code:

class Single
{
public:
	static Single &instance() 
	{
		static Single instance;

		return instance;
	}

private:
	Single() {}
	Single(const Single &);
	Single &operator=(const Single &);
};

so how do you acsses it ?
You still have to create and instance of the class in every *.cpp file your using it in...

I'm wonderng if i could create a class that behaves just like the one i wrote earlyer...
It's bothersome to write static in front of every data member and function, and you can't intialize data members inside the class.
So can anyone explain to me what does :

Code:

static class xxx
{
} yyy;

mean.
Is the yyy only instance, what happens here. I saw it in other people's codes...

Just read on static data members. I reckon singletons are too complex for you at this stage.

This:
> and there would be only one instance which you would acsses via :: operator

and this:
> but i still need to create an instance of class...

are incompatible.

You can however create a class that only has static data members and doesn't need to be instanced. You just access the class members as class::member... if taking head of your thread title and what I understod of your overall initial post

just explain to me what does

Code:

static class xxx
{
} yyy;

mean ?
That's all i want to know?

Originally Posted by Mario F.

This:
> and there would be only one instance which you would acsses via :: operator

and this:
> but i still need to create an instance of class...

are incompatible.

It should be incompatible, 'cause what i'm trying to say is :
* i want to acsses via :: operator
* i don't want to create and instance of the class

Is that really all you want to know?

yes, it is !

I'll try this one more time. Last one.

Read on static data members. It's as easy as googling for "c++ static data members".

And just so that we get this straight that static declaration you are showing is not what you want.

I don't know is it what i want, 'cause i don't know what it is. And i'm asking here what is it. And I gues you know what it is, but you don't want to say what it is...