title: Regular expressions for username and password
body: <p>Can you please help me with regular expressions. I need 2, one for username and one for password:</p>
  
  <p>Username one:</p>
  
  <ol>
  <li>Must be 8-15 characters and must start with a letter</li>
  <li>May not contain special characters – only letters and numbers      </li>
  </ol>
  
  <p>Password one:</p>
  
  <ol>
  <li>Must be 5-20 characters long</li>
  <li>Must contain at least one lower-case letter (abcdefghijklmnopqrstuvwxyz) </li>
  <li>Must contain at least one number (0123456789) </li>
  <li>Must not contain a colon (:); an ampersand (&amp;); a period (.); a tilde (~); or a space. </li>
  </ol>
  
  <p>Thank you for help.            </p>