title: PHP regular expression not being matched - what is wrong?
body: <p>I have the following regular expression:</p>
  
  <pre><code>"^[x]{1}[a-z]{3,4}:[a-z0-9]{1,6}"
  </code></pre>
  
  <p>I want to use it to be able to match strings like:</p>
  
  <p><strong>xabc:z123</strong></p>
  
  <p>However, when I try it with <a href="http://www.pagecolumn.com/tool/pregtest.htm" rel="nofollow">this regex tester</a>, it does not match the pattern. Is it my pattern that is wrong, or is the online tester unreliable?.</p>
  
  <p>If my pattern is wrong, could someone point out why it is wrong.</p>
  
  <p>Also, I want to make the pattern matching case insensitive - but I'm not too sure the best way to do that (thought better to ask rather than trial and error). How do I change the pattern so it matches irrespective of case?</p>