Highlight current menu item in PHP

Useful snippet for highlight current menu item in PHP

<ul class="sub-nav" > 

<?php

 $full_name = $_SERVER['PHP_SELF'];

 $name_array = explode('/',$full_name); 

$count = count($name_array); 

$page_name = $name_array[$count-1];

 ?> 

 <li>

              <a class="<?php echo ($page_name=='where-to-buy.php')?'active':'';?>" href="where-to-buy.php">WHERE TO BUY</a>

</li> 

<li>

            <a class="<?php echo ($page_name=='about.php')?'active':'';?>" href="about.php">ABOUT US</a>

</li> 

 <li>

                    <a class="<?php echo ($page_name=='contact.php')?'active':'';?>" href="contact.php">CONTACT US</a>

</li> 

 

</ul>