title: C++, constructor restrictions
body: <p>I'm studing C++ and I can't understand the meaning of the boldface sentence below:</p>
  <p>From <a href="http://publib.boulder.ibm.com/infocenter/lnxpcomp/v8v101/index.jsp?topic=/com.ibm.xlcpp8l.doc/language/ref/cplr389.htm" rel="noreferrer">IBM manual</a>:</p>
  <blockquote>
  <p>The following restrictions apply to constructors and destructors:</p>
  <ul>
  <li>Constructors and destructors do not have return types nor can they return values.</li>
  <li><strong>References and pointers cannot be used on constructors and destructors because their addresses cannot be taken.</strong></li>
  <li>Constructors cannot be declared with the keyword virtual.</li>
  <li>Constructors and destructors cannot be declared static, const, or volatile.</li>
  <li>Unions cannot contain class objects that have constructors or destructors.</li>
  </ul>
  </blockquote>
  <p>Could you please provide me an example?
  Thank you!</p>