title: RegEx to match characters from list except if characters another list are present
body: <p>I'm trying to build a regex to validate passwords in my application.</p>
  
  <p>This is PCRE (php).</p>
  
  <p>My regex so far looks like this</p>
  
  <pre><code>/^(?=.*[a-z])(?=.*[A-Z])(?=.*[0-9])(?=.*[!@#\$%\^&amp;\*\(\)_\+\-\=\[\]\{\}\|'])(?=.*[^\\\/])(?=.{8,20})/
  </code></pre>
  
  <p>And my criteria are the following</p>
  
  <pre><code>minimum length:            8
  maximum length:            20
  require special character: true
  require uppercase:         true
  require lowercase:         true
  require number:            true
  special character set:     !@#$%^&amp;*()_+-=[]{}|'
  excluded character set:    \/
  </code></pre>
  
  <p>Everything works but the excluded character set. The idea is the password must not contain any of the characters specified in that list.</p>
  
  <p>Thanks for the help</p>