title: PHP store old value and compare with new one
body: <p>I have a webpage that refreshes every X minute and shows some information from an array.</p>
  
  <pre><code>Name    Value
  -------------
  Mark     546
  Donald   312
  </code></pre>
  
  <p>My question is what is the easiest way to temporarily store the old value and compare it to the new value between page refreshes (see below)? It could be per user based simply when visiting the page. Php session and cookies maybe?</p>
  
  <pre><code>Name    Value Change
  --------------------
  Mark     559   +13
  Donald   233   -79
  </code></pre>