strpos

Hello everybody I am currently working on an rtf to html converter, and for this i need a function that can find a specific control word in the file. Because of the sheer number control words in the rtf standard, I have to be shure that I have the control word, by examining the trailing character. In som instanses there may be an number, but never another letter. Therefore I have made a loop, which currently is infinite ;) , that should keep on searching. I have but one litte problem, and that is strpos(). When I use the function bellow, and there is no occournce of the control word, strpos shoul return false, but instead i returns 1, which is not the intention. Does anybody here have an idea about what I am doing wring??? function _searchControlWord($word, $trailingNumber = false, $position = 0) {

       // We need the length to be able to examine the trailing character
       $wordLength = strlen($word);
             // Determine which regular expression is needed
       $trailingNumber ? $regex = "[a-zA-Z]" : $regex = "[a-zA-Z0-9]";
             // begin infinite loop, we will break out when we find it
       while (1) {
           // find position of occurrence and add one, we are not interested in the backslash
           // also helps ud when we need to find the next occurrence, if needed
           $position = strpos($this->fileContent, "\\".$word, $position) + 1;
           if ($position === false) return false;
                     // Examine trailing character
           $trailingCharacter = substr($this->fileContent, ($position + $wordLength), 1);
           echo $trailingCharacter." - ";
           if (!ereg($regex, $trailingCharacter)) {
               return $position;
           }
       }

}