的 包含打开的形式Application.OpenForms。如果该集合中的形式，然后将其打开。否则则不会打开（可能是封闭的）

 如果（Application.OpenForms.OfType< YouLikeHits_Settings方式>（）任何（） ）
 MessageBox.Show（打开表单）; 
，否则
 MessageBox.Show（形式是不是开）; 
 

How do I check if a form is open, and if it is open to close the form?

I tried the following, testing out some code but it keep saying the form is not open even when I know it is:

 foreach(Form a in Application.OpenForms) 
 {
     if (a is YouLikeHits_Settings) 
     {
         // About form is open
         MessageBox.Show("form open");
         break;
     }
     // About form is not open...
     MessageBox.Show("form not open");
     break;
 }

Application.OpenForms contains opened forms. If form in this collection, then it is opened. Otherwise it is not opened (possibly closed).

if (Application.OpenForms.OfType<YouLikeHits_Settings>().Any())
    MessageBox.Show("Form is opened");
else
    MessageBox.Show("Form is not opened");