title: i want some special character in password
body: <p>i wrote </p>
  
  <pre><code>$this-&gt;form_validation-&gt;set_rules(
      'password',
      'password',
      'required|min_length[4]|max_length[8]|regex_match[/^[a-z0-9]+$/]'
  );
  </code></pre>
  
  <p>but I want  :<br>
   Password must
  contain exactly 2
  special characters and
  2 uppercase letters</p>
  
  <p>how to write ?</p>