How to count all open forms of 1 specific class?

Question

I have a few Form-classes that derive from Form. And I want to count all open form instances of 1 special class like Form2. It's a simple WinForms application (no Mdi).

• Form1 (main)
• Form2 (can be many)
• Form3 (other forms)

The app can't be started multiple times. So it's just about counting the windows in this one application.

My ideas:

• Can Application give me a list of open windows ?
• WinApi, enumerate windows of 1 application ?
• put every new Form2 window into a list (I wish to avoid that)

Answer 1

Use Application.OpenForms property like:

int form2Count = Application.OpenForms.OfType<Form2>().Count();