windows - How should PHP memcached store values?

one text

I installed memcached (not memcache, it's memcacheD, which I installed), I added it to the php.ini file (extension=php_memcached.dll), the dll is fine, php doesn't threw any error, but when I wrote a small code to test it, it doesn't do anything... Here's the code:

<!DOCTYPE html>
<html>
<head>
  <title>Tesztoldal</title>
</head>
<body>
  <?php
$mc = new Memcached();
    $mc -> addServer("localhost", 11211);
    if ($content = $mc -> get('stg')) {
      echo var_dump($content);
    } else {
      $mc -> add('stg', array("stg1", "stg2", "stg3"), 36000);
    }
  ?>
</body>
</html>

I also tried with $mc -> set('stg', array... If I'm right, it should save that array for the first time, then when I refresh the page, it should load it from the cache and write it out. But it does not work. I found nowhere any tutorial, or anything, how it works. The examples, what I found would work with a single variable. They was like:

<?php
$mc = new Memcached();
$mc -> addServer("localhost", 11211);
$mc -> add('stg', array("stg1", "stg2", "stg3"));
$read_value = $mc -> get('stg');
?>

Okay, but that value lives for me until the script reaches its end. A simple variable could do that... I doN't really understand, how it should work. I read php.net, I read some articles, but nothing helped.

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