title: php string to xml
body: <p>I'm using php v5.3. I would like to convert a string to valid xml. Xml apparently requires '&amp;' characters to be encoded to <code>&amp;amp;</code> but all functions I can find which do this also convert characters like 'ë' to html entities xml doesn't accept (<code>&amp;euml;</code> in this case). What function should I use?</p>