title: Use C# regex to convert casing in a string
body: <p>how can I convert this string:</p>
  
  <p><code>bKk_035A_paint-House_V003</code><br>
  to<br>
  <code>BKK_035a_paint-House_v003</code>  </p>
  
  <p>with a regular expression (e.g. Regex.Replace)?<br>
  This regex matches the string: </p>
  
  <pre><code>^(?&lt;Group1&gt;[a-z][a-z0-9]{1,2})_(?&lt;Group2&gt;\d{3}[a-z]{0,2})_(?&lt;Group3&gt;[a-z-]+)_(?&lt;Group4&gt;v\d{3,5})$
  </code></pre>
  
  <ul>
  <li>Group1 = uppercase  </li>
  <li>Group2 = lowercase  </li>
  <li>Group3 = unchanged  </li>
  <li>Group4 = lowercase  </li>
  </ul>
  
  <p>Thanks for any help,<br>
  Patrick</p>