Run this test script:

<?php
    $mc = new Memcached;
    $mc->addServer("localhost", 11211);
    $mc->set("a", 1);
    var_dump($mc->get("a"));
?>

Make sure you have started your Couchbase, Membase or memcached server. Adjust the hostname and port as needed.

For more information, please see the API documentation.