Logout link for Joomla 1.5, 2.5 and 3.0

Joomla 1.5 Logout Link

<?php
$returnURL = base64_encode(JURI::root() . "");
$user =& JFactory::getUser();
echo 'Hi,'.$user->username;
?>
<a href="index.php?option=com_user&task=logout&return=<?php echo $returnURL; ?>">
<input type="button" name="Submit" class="button" value="Logout"></a>

Joomla 2.5 Logout Link


<a href="index.php?option=com_users&task=user.logout&<?php echo JUtility::getToken(); ?>=1">
<input type="button" name="Submit" class="button" value="Logout">
</a>


Joomla 3.0 Logout Link

//JUtility::getToken() has been removed in Joomla 3.0. Use JSession::getFormToken() instead.

<a href="index.php?option=com_users&task=user.logout&<?php echo JSession::getFormToken(); ?>=1">
<input type="button" name="Submit" class="button" value="Logout">
</a>

source  : http://rselvakumar.blogspot.com/2013/02/logout-link-for-joomla-15-and-25.html