title: what 's the difference between empty($val) and !$val?
body: <p>such as :</p>
  
  <pre><code>return empty(!$val);
  </code></pre>
  
  <p>and
      return !$val();</p>
  
  <p>of  just make a boolean condition such as:</p>
  
  <pre><code>if (!empty($val)) {}
  </code></pre>
  
  <p>and</p>
  
  <pre><code>if ($val) {}
  </code></pre>