Removing all buttons from form

Question

Hello all,

Why did one method work but the other did not and produce weird results?

I was trying to remove all controls of type button from a form.  I tried two methods:

This worked:

       public void ClearButtons()

        {

            for (int i = 0; i < this.Controls.Count; i++)

            {

                if (Controls[i] is Button)

                {

                    Controls.RemoveAt(i);

                    i--;

                }

            }

        }

Didn't work (I got weird results, some buttons would stay on the form):

  foreach(Control control in Controls)

                    {

                        if (control is Button)

                            Controls.Remove(control);

                    }