How to highlight current page in menu item?

Code:

<div id="menu">

         <ul>

            &lt;?php foreach ($tabMenu as $item) : ?&gt;

                &lt;?php echo buildListItem($item); ?&gt;

            &lt;?php endforeach; ?&gt;    

        </ul>

    </div>

Code:

function buildListItem($item) {

 $urlItemName = url_title($item->name, 'dash', TRUE); 

 $urlCatID = ($item->cat_id);

 $url = base_url() . $urlItemName. "/". $urlCatID;



 // item name is blog, add target into it 

 if ($urlItemName == 'blog') {

    $blog = "http://www.tumblr.com";

    return "<li><a href='" . $blog . "' target='_blank'>" . strtoupper($item->name) . "</a></li>";

 } else {

    return "<li class='". isSelected($item).  "'><a href='" . $url . "'>" . strtoupper($item->name) . "</a></li>";

 }

}



function isSelected($item) {

 $urlItemName = url_title($item->name, 'dash', TRUE);



 if ($this->uri->segment(1) === $urlItemName) {

    return 'menu_active';

 } else {

    return '';

 }

}