title: Check whether $_POST-value is empty
body: <pre><code>if(isset($_POST['submit'])) {
      if(!isset($_POST['userName'])) {
          $username = 'Anonymous';
      }      
      else $username = $_POST['userName'];
  }
  </code></pre>
  
  <p>I cannot get the <code>$username</code> to be "Anonymous"? It is either blank or the value of  <code>$_POST['userName']</code>.</p>