title: Compare two nullable dates
body: <p>I have two date properties and they are exactly the same as i am mapping from one object to another. If I compare them as below it returns false:</p>
  
  <pre><code>if(obj1.d1 == obj2.d1)
  {
  }
  </code></pre>
  
  <p>both of them are <code>{01/06/2011 15:44:32}</code>.</p>
  
  <p>I cannot use <code>DateTime.Compare</code> as they are nullable. what would be the best way to compare nullable dates?</p>