title: Best way to get all digits from a string
body: <p>Is there any better way to get take a string such as "(123) 455-2344" and get "1234552344" from it than doing this:</p>
  
  <pre><code>var matches = Regex.Matches(input, @"[0-9]+", RegexOptions.Compiled);
  
  return String.Join(string.Empty, matches.Cast&lt;Match&gt;()
                                  .Select(x =&gt; x.Value).ToArray());
  </code></pre>
  
  <p>Perhaps a regex pattern that can do it in a single match? I couldn't seem to create one to achieve that though.</p>