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gitbox 2025-07-21 
<span><span><span class="hljs-meta"><?php</span></span><span>
</span><span><span class="hljs-comment">// This part is unrelated code example</span></span><span>
</span><span><span class="hljs-title function_ invoke__">session_start</span></span><span>();
</span><span><span class="hljs-variable">$_SESSION</span></span><span>[</span><span><span class="hljs-string">'username'</span></span><span>] = </span><span><span class="hljs-string">'chatgpt'</span></span><span>;
</span><span><span class="hljs-variable">$_SESSION</span></span><span>[</span><span><span class="hljs-string">'email'</span></span><span>] = </span><span><span class="hljs-string">'[email protected]'</span></span><span>;
</span><span><span class="hljs-meta">?></span></span><span>
<p><hr></p>
<p></span><?php<br>
// Article starts here</p>
<p>/*<br>
【How to Use unset() to Clear PHP Session Variables? A Step-by-Step Guide】<br>
*/</p>
<p>echo "<h1>How to Use unset() to Clear PHP Session Variables? A Step-by-Step Guide</h1>";</p>
<p>// PHP session variables are used to store state information during a user's visit to a website, such as login status or user preferences.<br>
// Sometimes, we need to clear certain session variables or all session variables to prevent data leakage or incorrect information passing.</p>
<p></span>echo "<p>First, what is unset()?</p>";<br>
echo <span><span class="hljs-string">"<p>unset() is a built-in PHP function used to destroy a specified variable or array element. Using it, you can remove an element from the session array <code>$_SESSION
";
echo "

After execution, $_SESSION['username'] no longer exists.

";

echo "

Using unset() to Clear Multiple Session Variables

";
echo "

If you want to clear multiple specified session variables, you can call unset() multiple times, for example:

";
echo "
<br>
unset($_SESSION['username']);<br>
unset($_SESSION['email']);<br>
";

echo "

Why Not Use unset() to Clear All Session Variables?

";
echo "

Although you can unset each key one by one, if you want to clear the entire session, it’s recommended to use session_unset() or $_SESSION = array();, which is more efficient and concise.

";

echo "

The Correct Way to Clear All Session Variables

";
echo "
<br>
session_unset(); // Clears all session variables<br>
// or<br>
$_SESSION = array(); // Resets the session array to empty<br>
";

echo "

Summary

";
echo "
    ";
    echo "
  • Use unset($_SESSION['key']); to delete a single session variable.
    • "    ;
    echo "
  • Use session_unset() or $_SESSION = array(); to clear all session variables.
    • "    ;
    echo "
  • Note: Clearing session variables is not the same as destroying the session; to destroy the session, use session_destroy().
    • "    ;
    echo "
";

echo "

Mastering these methods will help you better manage PHP session variables, ensuring your program’s security and logical correctness.

";

?>

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