title: Getting a list of files in order of the last 10 characters
body: <p>I wish to sort my files in order of the last 10 characters of the filename, and I would like to do it in one instruction.</p>
  
  <pre><code>// this works
  
  string s = "...blabla20140129.u", s2 = s.Substring(s.Length - 10,8);
  
  // this fails with the message
  var directory = new DirectoryInfo(dir).GetFiles(fileSpec).OrderBy(f =&gt; f.FullName.Substring(f.FullName.Length - 10),8);
  
  Error   1   The type arguments for method 'System.Linq.Enumerable.OrderBy&lt;TSource,TKey&gt;(System.Collections.Generic.IEnumerable&lt;TSource&gt;, System.Func&lt;TSource,TKey&gt;, System.Collections.Generic.IComparer&lt;TKey&gt;)' cannot be inferred from the usage. Try specifying the type arguments explicitly.   
  </code></pre>
  
  <p>It must be solved using .net 3.5 or less</p>
  
  <p>Any advice is appreciated.</p>