What does "??" mean?
<p>I'm looking at the generated code by ASP.NET MVC 1.0, and was wondering; what do the double question marks mean?</p>

<pre><code>// This constructor is not used by the MVC framework but is instead provided for ease
// of unit testing this type. See the comments at the end of this file for more
// information.
public AccountController(IFormsAuthentication formsAuth, IMembershipService service)
{
    FormsAuth = formsAuth ?? new FormsAuthenticationService();
    MembershipService = service ?? new AccountMembershipService();
}
</code></pre>

<h3>Related:</h3>

<blockquote>
  <p><a href="http://stackoverflow.com/questions/770186/-null-coalescing-operator-what-does-coalescing-mean">?? Null Coalescing Operator —> What does coalescing mean?</a></p>
</blockquote>
