Bad solution, but I don't know any other.
I don't know if WordPress can do this alone, but php can
you have to put the result of this function into a variable, and use a function like that (I translate the code for you) :
<?php
/******************************************************************************/
/* */
/* __ ____ */
/* ___ / / ___ / __/__ __ _____________ ___ */
/* / _ \/ _ \/ _ \_\ \/ _ \/ // / __/ __/ -_|_-< */
/* / .__/_//_/ .__/___/\___/\_,_/_/ \__/\__/___/ */
/* /_/ /_/ */
/* */
/* */
/******************************************************************************/
/* */
/* Titre : find a character in a string */
/* */
/* URL : http://www.phpsources.org/scripts154-PHP.htm */
/* Auteur : PHP Sources */
/* Date édition : 04 Jan 2006 */
/* */
/******************************************************************************/
$my_string = 'abcefghigkmnlopqrstuvwxyz'; // put your variable containing your .doc instead $my_string
$find_me = 'a'; // put the search instead $find_me
$position = strpos($my_string, $find_me);
// you have to use === because == won't display anything
// because the letter 'a' is in position 0
if ($position === false) {
echo '',$find_me,' not found in ',$my_string,'';
} else
{
echo '',$find_me,' in in ',$my_string,'';
echo 'in position ',$position,'';
}
?>
if the translated code don't work, try to use the original - maybe I've make a mistake.