title: what is "?? "operator in c#?
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/827454/what-is-the-operator-for">What is the &ldquo;??&rdquo; operator for?</a>  </p>
  </blockquote>
  
  
  
  <p>What does the "??" operator perform in an expression ?</p>
  
  <pre><code>public NameValueCollection Metadata
  {
      get { return metadata ?? (metadata = new NameValueCollection()); }
  }
  </code></pre>