title: Regular Expressions - Filtering alphabetic and non-alphanumeric characters
body: <p>I need to filter alphabetic and non alphanumeric characters from a string to make it an integer.</p>
  
  <p>What is the difference between the regular expression strings </p>
  
  <pre><code>\w
  </code></pre>
  
  <p>and </p>
  
  <pre><code>\w*
  </code></pre>
  
  <p>?</p>