/**

     *    String from columnindex

     *

     *    @param    int $pColumnIndex Column index (base 0 !!!)

     *    @return    string

     */

    public static function stringFromColumnIndex($pColumnIndex = 0)

    {

        //    Using a lookup cache adds a slight memory overhead, but boosts speed

        //    caching using a static within the method is faster than a class static,

        //        though it's additional memory overhead

        static $_indexCache = array();

        if (!isset($_indexCache[$pColumnIndex])) {

            // Determine column string

            if ($pColumnIndex < 26) {

                $_indexCache[$pColumnIndex] = chr(65 + $pColumnIndex);

            } elseif ($pColumnIndex < 702) {

                $_indexCache[$pColumnIndex] = chr(64 + ($pColumnIndex / 26)) .

                                              chr(65 + $pColumnIndex % 26);

            } else {

                $_indexCache[$pColumnIndex] = chr(64 + (($pColumnIndex - 26) / 676)) .

                                              chr(65 + ((($pColumnIndex - 26) % 676) / 26)) .

                                              chr(65 + $pColumnIndex % 26);

            }

        }

        return $_indexCache[$pColumnIndex];

    }