title: How do I check whether an item exists in Listbox in asp.net?
body: <p>How do I check whether an item already exists in a Listbox?<br>
  I am using VS 2008 ASP.NET 3.5 framework C#. I used the following code...</p>
  
  <pre><code> if (ListBox1.Items.Contains(drp_branch.SelectedItem.Value + "-" + txt_acc_no.Text))
   {...}
  </code></pre>