isInteger example

$locale        = localeconv();
            $valueFiltered = str_replace($locale['decimal_point'], '.', $value);
            $valueFiltered = str_replace($locale['thousands_sep'], '', $valueFiltered);

            if (strval(intval($valueFiltered)) != $valueFiltered) {
                $this->_error(self::NOT_INT);
                return false;
            }

        } else {
            try {
                if (!Zend_Locale_Format::isInteger($value, array('locale' => $this->_locale))) {
                    $this->_error(self::NOT_INT);
                    return false;
                }
            } catch (Zend_Locale_Exception $e) {
                $this->_error(self::NOT_INT);
                return false;
            }
        }

        return true;
    }
}