title: Find where Regex.Match failed
body: <p>I want to know which Regex Groupcollection failed to match.</p>
  
  <p>e.g.:</p>
  
  <p>My pattern detects <code>VIEW start page</code> or <code>VIEW end</code> via:</p>
  
  <pre><code>match = Regex.Match(string, @"(^VIEW)\s*((?(1)(?:(start)\s*((?(1)page$))|(end$))))");
  </code></pre>
  
  <p>I want to know if I give the input string as "VIEW go" how to find that the second group failed.</p>