title: Regex to match alphanumeric and spaces
body: <p>What am I doing wrong here?</p>
  
  <pre><code>string q = "john s!";
  string clean = Regex.Replace(q, @"([^a-zA-Z0-9]|^\s)", string.Empty);
  // clean == "johns". I want "john s";
  </code></pre>