title: How can I use RegEx to differentiate between screen resolutions?
body: <p>I'm trying to create a RegEx expression that will match a numeric range from 0 to 600 so I can easily differentiate between a small mobile device and tablets/desktops. I'm using Qualtrics' survey software to do the rest - all I need is the RegEx expression.</p>
  
  <p>However, I'm not 100% sure how Qualtrics takes in the data. I believe it takes it in the following format:</p>
  
  <pre><code>360x640
  320x568
  320x480
  1920x1080
  360x640
  1280x800
  320x568
  1920x1080
  360x640
  1280x800
  1920x1080
  480x800
  320x480
  1280x800
  1366x768
  320x568
  1280x800
  </code></pre>
  
  <p>Where I'm testing the FIRST number, e.g. the number before the 'x' character.</p>
  
  <p>Here's some RegEx I've tried that did not work:</p>
  
  <pre><code>([0-9]{1,2}|[1-4][0-9]{2}|600)*x
  </code></pre>
  
  <p>That code recognizes numbers before the 'x', but it doesn't stop at 600 - it recognizes all numbers before the 'x' (e.g. from 000 to 9999).</p>
  
  <p>How do I get the range I want? Please and thank you!</p>
  
  <p>Note: I've tried using the RegEx number range generator <a href="http://utilitymill.com/utility/Regex_For_Range" rel="nofollow">here</a>, but it doesn't work for what I want to accomplish.</p>