title: PHP - Don't repeat random selection
body: <p>I have a small PHP script that is selecting a random sentence from an array</p>
  
  <pre><code>$prefixes = array('sentence 1', 'sentence 2');
  
  echo $prefixes[rand(0,count($prefixes)-1)];
  </code></pre>
  
  <p>How can I make it not pick the same sentence twice in a row?</p>
  
  <p>Edit: Sorry, yeah there will be around 100 sentences and they can be used over and over again just not twice in a row. It's an on click event that re-loads the sentence to the page with AJAX and if it picks the same sentence twice in a row it looks like clicking the button hasn't done anything as there is no page refresh. Thanks</p>
  
  <p>Edit 2: Basically it's a DIV with a sentence in, when you click a button it loads a new sentence into the DIV via AJAX and replaces the old sentence with the new one. Sometimes it was loading the same sentence twice in a row which gave the effect the button wasn't doing anything</p>