title: Regex -> only letters and end with a dot
body: <p>I'm trying to select all the tokens that contain only letters or only letters and end with a dot.</p>
  
  <p>Example of valid words : <code>"abc", "abc."</code><br>
  Invalid <code>"a.b" "a2"</code></p>
  
  <p>i've tried this</p>
  
  <pre><code>string[] tokens = text.Split(' ');
  var words = from token in tokens 
              where Regex.IsMatch(token,"^[a-zA-Z]+.?$")
              select token;
  </code></pre>
  
  <p><code>^[a-zA-Z]+</code>  - only letters one or more times and start with letter</p>
  
  <p><code>.?$</code> = ends with 0 or 1 dot ?? not sure about this</p>