title: Why is base64_encode() adding a slash "/" in the result?
body: <p>I am encoding the URL suffix of my application:</p>
  <pre><code>$url = 'subjects?_d=1';
  echo base64_encode($url);
  
  // Outputs
  c3ViamVjdHM/X2Q9MQ==
  </code></pre>
  <p>Notice the slash before 'X2'.</p>
  <p>Why is this happening?  I thought base64 only outputted A-Z, 0-9 and '=' as padding?</p>