title: Regex word boundary expressions
body: <p>Say for example I have the following string <code>"one two(three) (three) four five"</code> and I want to replace <code>"(three)"</code> with <code>"(four)"</code> but not within words. How would I do it?</p>
  
  <p>Basically I want to do a regex replace and end up with the following string:</p>
  
  <pre><code>"one two(three) (four) four five"
  </code></pre>
  
  <p>I have tried the following regex but it doesn't work:</p>
  
  <pre><code>@"\b\(three\)\b"
  </code></pre>
  
  <p>Basically I am writing some search and replace code and am giving the user the usual options to match case, match whole word etc. In this instance the user has chosen to match whole words but I don't know what the text being searched for will be.</p>