C++ Classes constructor

If i have a class name Class. The the function "Class" is called for every instance of the class when it starts, and "~Class" is class is called for every instance when it exits. My question is, is there a function that gets called only once when it starts, no matter how many instances of the class?

I ask this because im making a window into a class and in the constuctor i register the window class. I figure this might cause problems if theres more than one instance of the class. Or its just kind of a waste to register the window more than once.

You can use a static variable as a counter in your class. If it's 0, then you register the class, and if it's larger than 0, then you won't.
Don't forget to increment or decrement it every time a new instance is created or destroyed, so you're able to deregister the class if it's necessary, when the counter is 0.

Quote:

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Originally posted by ChimpFace9000
If i have a class name Class. The the function "Class" is called for every instance of the class when it starts, and "~Class" is class is called for every instance when it exits. My question is, is there a function that gets called only once when it starts, no matter how many instances of the class?

I ask this because im making a window into a class and in the constuctor i register the window class. I figure this might cause problems if theres more than one instance of the class. Or its just kind of a waste to register the window more than once.

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The Singleton pattern might help you here. The idea is that you have a private constructor, and you request the object which is created statically:

Code:

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class Singleton {
public:
    inline Singleton& instance() {
        static Singleton myself;

        return myself;
    }

private:
    inline Singleton() { }
};

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...is this the sort of thing you need?

parksie: Im not sure what you mean.
riis: PERFECT!!! Its so simple, i cant believe i didnt think of that.

It means you'll only ever have one "instance" of that class.