title: C# foreach only get distinct values
body: <p>I have the following code:</p>
  
  <pre><code>foreach (Logs log in _logsDutyStatusChange)
  {
      string driverid = log.did;
  }
  </code></pre>
  
  <p>How would I only add distinct driver ID's to the driverid string?</p>
  
  <p>Thanks</p>