title: Regular Expression allowing special characters
body: <p>I am using the following pattern to match my String:</p>
  
  <blockquote>
    <p>[a-zA-Z0-9]*</p>
  </blockquote>
  
  <p>Even when I am passing the String <code>*$#</code>, its getting matched by the regular expression. Could someone explain what am I doing wrong or why this is happening?</p>