title: regex for matching two or more numbers, then one 'x', then two or more numbers
body: <p>I'm having trouble constructing this regex. I need a strpos or a preg_match that will match the following pattern: <code>00x00.</code> where the '0's are any number(s), and x is upper or lowercase, then a period.</p>
  
  <p>I know I can do \d for numbers, but don't know how to specify two or more numbers. I know I can do [xX] for either upper or lowercase 'x', and I'm lost on the period.</p>
  
  <p>I've tried this:</p>
  
  <pre><code>preg_match ( '/\\d[xX]\\d\./', $string )
  </code></pre>
  
  <p>but that isn't working. </p>
  
  <p>I'd prefer to do it with a strpos, but either is fine. </p>
  
  <p>EDIT - The period is optional; it's just added security. But I'm not sure if it's possible to match it not knowing how many numbers are between the 'x' and the period.</p>