require_once( Horder/Autoloader.php );
$autoloader = new Horde_Autoloader();

$text_diff = $autoloader->loadClass( 'Hoard_Text_Diff' );

require_once 'Horde/Autoloader.php';
require_once 'Horde/Autoloader/ClassPathMapper.php';
require_once 'Horde/Autoloader/ClassPathMapper/Default.php';

$autoloader = new Horde_Autoloader();
$autoloader->addClassPathMapper(new Horde_Autoloader_ClassPathMapper_Default(__DIR__.'PATH_TO_HORDE_FOLDER'));
$autoloader->registerAutoloader();

// if path is correct autoloader should work
$diff = new Horde_Text_Diff();

// set the current path to your include_path
set_include_path(__DIR__.'PATH_TO_HORDE_FOLDER');

// if you require the default autoloader it will get initialized automatically
require_once 'Horde/Autoloader/Default.php';

// use the lib
$diff = new Horde_Text_Diff();

// this file:
// C:xampphtdocshordeindex.php

// horde folder structure
// C:xampphtdocshordelibHordeAutoloader
// C:xampphtdocshordelibHordeText

require_once __DIR__.'/lib/Horde/Autoloader.php';
require_once __DIR__.'/lib/Horde/Autoloader/ClassPathMapper.php';
require_once __DIR__.'/lib/Horde/Autoloader/ClassPathMapper/Default.php';

$autoloader = new Horde_Autoloader();
$autoloader->addClassPathMapper(new Horde_Autoloader_ClassPathMapper_Default(__DIR__.'/lib'));
$autoloader->registerAutoloader();

$compare = array(
    array(
        'foo',
        'bar',
        'foobar'
    ),
    array(
        'foo',
        'bar',
        'foobaz'
    ),
);

$diff = new Horde_Text_Diff('auto', $compare);

echo '<pre>';
print_r($diff->getDiff());
echo '</pre>';