title: What does a double question mark do in C#?
body: <blockquote>
    <p><strong>Possible Duplicates:</strong><br>
    <a href="https://stackoverflow.com/questions/770186/-null-coalescing-operator-what-does-coalescing-mean">?? Null Coalescing Operator --&gt; What does coalescing mean?</a><br>
    <a href="https://stackoverflow.com/questions/446835/what-do-two-question-marks-together-mean-in-c">What do two question marks together mean in C#?</a>  </p>
  </blockquote>
  
  <p>I couldn't find this question being asked here so I figured I would ask it. What does a double question mark do in C#?</p>
  
  <p>Example:</p>
  
  <pre><code>x = y ?? z;
  </code></pre>