title: Regular expressions for a range of unicode points PHP
body: <p>I'm trying to strip all characters from a string except:</p>
  
  <ul>
  <li>Alphanumeric characters</li>
  <li>Dollar sign (<code>$</code>)</li>
  <li>Underscore (<code>_</code>)</li>
  <li>Unicode characters between code points <code>U+0080</code> and <code>U+FFFF</code></li>
  </ul>
  
  <p>I've got the first three conditions by doing this:</p>
  
  <pre><code>preg_replace('/[^a-zA-Z\d$_]+/', '', $foo);
  </code></pre>
  
  <p>How do I go about matching the fourth condition? <a href="https://php.net/manual/en/regexp.reference.unicode.php" rel="noreferrer">I looked at using <code>\X</code></a> but there has to be a better way than listing out 65000+ characters.</p>