C# Why does form.Close() not close the form?

I have a button click event handler with the following pseudo code:

private void btnSave_Click(object sender, EventArgs e)
{
  if(txt.Text.length == 0)
     this.Close();
  else
     // Do something else

  // Some other code...
}

This is just some simple code, but the point is, when the text length equals zero, I want to close the form. But instead of closing the form the code executes the part // S开发者_开发百科ome other code. After the click event handler is completely executed, then the form is closed.

I know, when I place return right after this.Close() the form will close, but I'd like to know WHY the form isn't direclty closed when you call this.Close(). Why is the rest of the event handler executed?

The rest of the event handler is executed because you did not leave the method. It is as simple as that.

Calling this.Close() does not immediately "delete" the form (and the current event handler). The form will be collected later on by the garbage collector if there are no more references to the form.

this.Close() is nothing than a regular method call, and unless the method throws an exception you will stay in the context of your current method.

Close only hides the form; the form is still alive and won't receive another Load event if you show it again.

To actually delete it from memory, use Dispose().

Answer is simple as you are executing your current method so this.Close() will be enqueued until either you explicitly returned or your current excuting method throws an exception.

Another possible solution is that if you open a new Form and want to close the current one: if you use newForm.ShowDialog() instead of newForm.Show() it doesn't close the currentForm with currentForm.Close() until the newForm is also closed.

Unless the Form is a modal form(opened with .ShowDialog()), Form.Close() disposes the form, as well. So, you cannot reopen it under any circumstances after that, despite of what others may have said. There is Form.Visible for this behavior(hiding/showing the form).

The point here is that .Close() does not return from the section it is called for several reasons. For example, you may call SomeForm.Close() from another form or a class or whatever.

Close() is just a method like any other. You have to explicitly return from a method that calls Close() if this is what you want.

Calling MessageBox.Show(frmMain,"a message","a title") adds the form "TextDialog" to the application's Application.OpenForms() forms collection, along-side the frmMain Main form itself. It remains after you close the Messagebox.

When this happens and you call the OK button delegate to close the main form, calling frmMain.Close() will not work, the main form will not disappear and the program will not terminate as it usually will after you exit the OK delegate. Only Application.Exit() will close all of the garbage messagebox "TextDialog"s.

private void btnCloseForm_Click(object sender, EventArgs e)
{
FirstFrm.ActiveForm.Close();
}

and if you want close first form and open secound form do this :

private void btnCloseForm_Click(object sender, EventArgs e)
{
FirstFrm.ActiveForm.Close();
}

private void FirstFrm_FormClosed(object sender, FormClosedEventArgs e)
{
SecounfFrm frm = new SecounfFrm ();
frm.ShowDialog();
}

or you can do somting like that :

private void btnCloseForm_Click(object sender, EventArgs e)
{
this.Hide();
}

private void FirstFrm_VisibleChanged(object sender, EventArgs e)
{
if(this.Visible == false)
{
this.Close();
}
}

private void FirstFrm_FormClosed(object sender, FormClosedEventArgs e)
{
SecounfFrm frm = new SecounfFrm ();
frm.ShowDialog();
}