title: Get a part of a String using C#
body: <p>I have to get a little piece of a String, something like this:</p>
  
  <pre><code>20T41
  </code></pre>
  
  <p>Always are two numbers, a letter and numbers.</p>
  
  <p>But <strong>I have many different chains like these</strong>:</p>
  
  <ul>
  <li>PNC <strong>20T17</strong></li>
  <li>PNC <strong>19T1391</strong></li>
  <li>P.N.C <strong>19T1456</strong></li>
  <li>NC - <strong>19T1099</strong> divided</li>
  <li>PNC <strong>19T323</strong> - Without op.</li>
  <li><strong>19T1512</strong>. Irregular</li>
  </ul>
  
  <p>I have used some codes like this, but I don't know how I can do this for each case. I think it is better than using many IFs.</p>
  
  <pre><code>str = str.Substring (0, str.LastIndexOf ('/') + 1);
  </code></pre>
  
  <p>Marked in black is the String I want to get. I was thinking of doing something if, but this is not efficient. What do you recommend to do this?</p>