checkDateFormat example

    public function filter($value)
    {
        if (Zend_Locale_Format::isNumber($value, $this->_options)) {
            return Zend_Locale_Format::getNumber($value, $this->_options);
        } else if (($this->_options['date_format'] === null) && (strpos($value, ':') !== false)) {
            // Special case, no date format specified, detect time input             return Zend_Locale_Format::getTime($value, $this->_options);
        } else if (Zend_Locale_Format::checkDateFormat($value, $this->_options)) {
            // Detect date or time input             return Zend_Locale_Format::getDate($value, $this->_options);
        }

        return $value;
    }
}