title: std::string::iterator to offset and back
body: <ul>
  <li>Can I set an iterator to position 5 in a string via some member or do I have to do a <code>for(i = 0; i &lt; 5; ++i) iterator++;</code>?</li>
  <li>Given an Iterator, how can I convert that to a numeric offset in the string?</li>
  <li>If this is not possible with std::iterators can boost do it?</li>
  </ul>
  
  <p>Iterators &lt;-> Offsets</p>