title: What algorithm does arsort use?
body: <p>The <a href="http://php.net/manual/en/function.arsort.php" rel="nofollow">doc</a> doesnt seem to tell us what algorithm is used for array sorting. So what algorithm does the function arsort use? In otherwords, does it use merge sort, quick sort?</p>
  
  <p>Code taken from doc:</p>
  
  <pre><code>&lt;?php
  $fruits = array("d" =&gt; "lemon", "a" =&gt; "orange", "b" =&gt; "banana", "c" =&gt; "apple");
  arsort($fruits);
  foreach ($fruits as $key =&gt; $val) {
      echo "$key = $val\n";
  }
  </code></pre>
  
  <p>Output:</p>
  
  <pre><code>a = orange
  d = lemon
  b = banana
  c = apple
  </code></pre>