Mengatasi fatal error crud menggunakan xml

kenapa ya kok saya run ada tulisan Warning: require(simplexml.class.php): failed to open stream: No such file or directory in C:\xampp\htdocs\crudxml\view.php on line 2

Fatal error: require(): Failed opening required 'simplexml.class.php' (include_path='C:\xampp\php\PEAR') in C:\xampp\htdocs\crudxml\view.php on line 2

<?php
require('simplexml.class.php');
if($_GET['act']=='hapus'){
$product = simplexml_load_file('product.xml');
$id = $_GET['id'];
$index = 0;
$i= 0;
foreach($product->product as $produk){
if($produk->id_produk == $id){
$index = $i;
break;
}
$i++;
}
unset($product->product[$index]);
file_put_contents('product.xml',$product->asXml());

}

$product = simplexml_load_file('product.xml');
$json = json_encode($product);
$array = json_decode($json,TRUE);
$jumlah = count($array);
$no=1;
echo"<a href='add.php'> <button>add</button> </a> <br><br>";
echo "<table border=0 width=100% style='padding:15px; border:1px solid #000;'> ";
echo "<tr bgcolor='#ccc'> <td>No</td> <td>Nama</td> <td>Harga</td> <td>Edit</td> <td>Hapus</td></tr> ";
foreach($product->product as $produk ){
if(($no%2)==0){
$warna="#ccc";
}else{
$warna="#fff";
}
echo "<tr bgcolor='$warna'><td>".$no."</td>";
echo "<td>".$produk->name."</td>";
echo "<td>".$produk->price."</td>";
echo "<td><a href='edit.php?id=".$produk->id_produk."'> <button>Edit</button></a></td>";
echo "<td><a href='index.php?act=hapus&id=".$produk->id_produk."'><button>Delete</button></a></td></tr>";
$no++;
}
echo" </table>";
?>

mohon solusinya. full link code saya ambil dari sini https://topidesta.wordpress.com/2016/04/29/crud-php-dan-xml-2-0/