关闭除我的主表单以外的所有表单

Question

I'm using WinForms . I want to close all of the forms except my main form called Form1 . I noticed that my main Form is index 0, so i was wondering if i could do something like, close all the forms except of index 0. How can i do this? This is what i have so far.

 List<Form> openForms = new List<Form>();

  foreach (Form f in Application.OpenForms)
  {
        openForms.Add(f);
        int mainFormIndex = openForms.IndexOf(0);
        Console.WriteLine(": " + mainFormIndex);


        if(mainFormIndex != 0)
        {
           this.Owner.Close();
           }
           else
           {
             this.Close();
           }
        }
  }

Answer 1

You can close all forms except Form1 instance using linq this way:

Application.OpenForms.Cast<Form>().Where(x => !(x is Form1))
           .ToList().ForEach(x => x.Close());

Answer 2

You can check the name of Form and then close, for example if you need to keep Form1 open and close all other forms;

for (int i = Application.OpenForms.Count - 1; i >= 0; i--)
{
    if (Application.OpenForms[i].Name != "Form1")
    {
        Application.OpenForms[i].Close();
    }
}