title: what in PHP is similar to Actionscript 's "is" operator?
body: <p>As far I know the <strong>is</strong> operator in ActionScript does the following: (rectify me, if I am wrong)</p>
  
  <ol>
  <li><p>Tests whether a variable or expression is compatible with a given data type.</p></li>
  <li><p>Examines the inheritance hierarchy </p></li>
  <li><p>Can be used to check whether an object is an instance of a particular class or a child (or grandchild, great grandchild, great great grandchild, and so on) of a particular class. </p></li>
  <li><p>Check whether an object is an instance of a class that implements a particular interface</p></li>
  </ol>
  
  <p>Now I want to know what in <strong>PHP</strong> is/are similar to Actionscript 's "<strong>is</strong>" operator? </p>