检查MDIcontainer是否为空

Question

I just stuck in a very simple situation bt couldnt help myself.My question is How to do i check whether my mdiparent contains the child form or not? help will be appreciated.

Answer 1

You can use the ActiveMdiChild property of your parent form.

It will be null if the parent does not contain any MDI child form.

Answer 2

For the title of your question:

int formCount = this.MdiChildren.Count(); \\ or .Length
MessageBox.Show("I have " + formCount.ToString() + " child forms open.");

For the other part of your question:

Form2 f2 = new Form2();
f2.MdiParent = this;
f2.Show();

if (this.MdiChildren.Contains(f2))
  MessageBox.Show("Form2 f2 is opened");