title: listbox; number of selected items
body: <p>While using listbox in c#, how can learn the count of selecteditems?</p>
  
  <p>Listbox items: A,B,C,D. For example, I select C and D. </p>
  
  <p>I want to make a loop in order to assign selecteditems.</p>
  
  <p>How can I achieve it? How can I learn the number of selected item?</p>
  
  <p>Thank you</p>