PHP check if $_SESSION['text'] is text
<p>How can I check check that <code>$_SESSION['text']</code> is indeed text and not some malicious .exe?</p>

<p><strong>AND</strong>, if i do destroy_session(...) but set </p>

<pre><code>$a = $_SESSION;
</code></pre>

<p>does $a become NULL now?</p>
