how to rar files unrar through php script

[hyungKim]

<?php
$rar_arch = RarArchive::open('', '');
if ($rar_arch === FALSE)
    die("Failed opening file");
 
$entries = $rar_arch->getEntries();
if ($entries === FALSE)
    die("Failed fetching entries");
 
echo "Found " . count($entries) . " ";
 
if (empty($entries))
    die("No valid entries found.");
 
$stream = reset($entries)->getStream();
if ($stream === FALSE)
    die("Failed opening first file");
 
$rar_arch->close();
 
echo "Content of first one follows:\n";
echo stream_get_contents($stream);
 
fclose($stream);
?> 

Error is:
Fatal error: Class 'RarArchive' not found in C:\Zend\Apache2\htdocs\CSV\email1.php on line 2 .....