title: regex check for white space in middle of string
body: <p>I want to validate that the characters are alpha numeric:</p>
  
  <pre><code>Regex aNum = Regex("[a-z][A-Z][0-9]");
  </code></pre>
  
  <p>I want to add the option that there might be a white space, so it would be a two word expression:</p>
  
  <pre><code>Regex aNum = Regex("[a-z][A-Z][0-9]["\\s]");
  </code></pre>
  
  <p>but couldn't find the correct syntax.</p>
  
  <p>id applicate any incite.</p>