title: Regex for single digit catches two digit numbers?
body: <p>This regex catches two digit nubers:</p>
  <p>if I have y11 it will still catch it, how to match only y0, y1, y2, y3, y4, y5, y6, y7, y8, y9 ?? After the digit there might be a blank space or a letter or a dot.</p>
  <pre><code>preg_replace('/y([1-9]{1})/', 'y0$1', $string)
  </code></pre>