title: How to check if a value already exist in list box before adding to it in asp.net
body: <p>how can I check if the value is already present in a list-box, so that I can avoid duplicates? </p>
  
  <p>I've added some values to the server-side list-box already, and when I add to list I get more duplicates. </p>
  
  <p>How do I avoid duplicates?</p>
  
  <pre><code>lst_Viewers.Items.Add(reader["Name"].ToString());
  </code></pre>