Обрезания строки до слова

            if($arParams["PREVIEW_TRUNCATE_LEN"]>0 && $arItem["PREVIEW_TEXT_TYPE"]!="html")
            {   
                $end_pos = $arParams["PREVIEW_TRUNCATE_LEN"];
                while(substr($arItem["PREVIEW_TEXT"],$end_pos,1)!=" " && $end_pos<strlen($arItem["PREVIEW_TEXT"]))
                    $end_pos++;
                if($end_pos<strlen($arItem["PREVIEW_TEXT"]))
                    $arItem["PREVIEW_TEXT"] = substr($arItem["PREVIEW_TEXT"], 0, $end_pos)."...";
            }