title: Regular Expression for matching XML tags and replacing node values
body: <pre class="lang-xml prettyprint-override"><code>&lt;conf-start iso-8601-date="2011-05-31"&gt;
     &lt;day&gt;31&lt;/day&gt;&lt;month&gt;May&lt;/month&gt;&lt;year&gt;2011&lt;/year&gt;
  &lt;/conf-start&gt;
  </code></pre>
  
  <p>this is the given XML expression and I just wanna replace the <code>&lt;month&gt;May&lt;/month&gt;</code> to <code>&lt;month&gt;05&lt;/month&gt;</code> I know it can be done by regular expression but the problem is that I am not that much familiar with regular expressions.</p>
  
  <p>Please, anyone help me with an expression.  </p>