title: What does __uuidof(someVar) do?
body: <p>I found some code which is meant to call <code>__uuidof(IMyInterface)</code> but actually calls <code>__uuidof(pIMyInterface)</code> where <code>pIMyInterface</code> is a pointer of type <code>IMyInterface</code>. How does <code>__uuidof</code> behave when called on a value rather than a type?</p>
  
  <p>e.g. <code>int x=123; __uuidof(x)</code> is this equivalent to <code>__uuidof(int)</code> or <code>__uuidof(123)</code></p>