title: In a C++ application in Mac or Windows, is there a way to determine if a given ProcessId still exists?
body: <p>I have a QT application that runs on both Windows and Mac. Is there a way  to provide a PID, and get back:</p>
  <ol>
  <li>If the PID exists</li>
  <li>The name of the process under that PID</li>
  </ol>
  <p>For Windows I thing I can use <code>EnumProcesses()</code> to find out what I need, but how can this be done on Mac?</p>