c# - How to get or Kill all instances from certain class?

Question

How can I get all instances from a certain class or kill all instances of certain class?

For Example, I've a Class MyClass which I intantiate three times as m1, m2 and m3.

Is there a way to get or kill all these instances?

more clarification : when I've a "settings form" class. When the user click Settings button the application makes instance from this class. When he clicks the same button again it makes new instance. I want it show the 1st instance only and not making new instance

Answer 1

Not that i'm aware, but you can save the instance when constructing the object on some sort of collection so you can access all instances later:

public class MyClass {
    public static List<MyClass> instances = new List<MyClass>();
    public MyClass() {
        instances.Add(this);
    }
}

EDIT:

Save the settings class as a field for the form, and when clicking button, check if that field is null; if so, instantiate

public class Form1 : Form {
    private SettingsClass settings;

    ...
    ...

    private void btnSettings_Click(object sender, EventArgs e) {
        if (settings == null) {
            settings = new SettingsClass();
        } else {
            // do nothing, already exists
        }

        // use settings object
    }
}