title: Split alphanumeric string between leading digits and trailing letters
body: <p>I have a string like:</p>
  <pre><code>$Order_num = &quot;0982asdlkj&quot;;
  </code></pre>
  <p>How can I split that into the 2 variables, with the number as one element and then another variable with the letter element?</p>
  <p>The number element can be any length from 1 to 4 say and the letter element fills the rest to make every order_num 10 characters long in total.</p>
  <p>I have found the php <code>explode</code> function...but don't know how to make it in my case because the number of numbers is between 1 and 4 and the letters are random after that, so no way to split at a particular letter.</p>