$jinput = JFactory::getApplication()->input;
        $post = $jinput->getArray($_POST);
                $code = $post["g_recaptcha_response"]; //here we have the catcha code to validate
                //call captcha plugin to validate code
                JPluginHelper::importPlugin('captcha');
                $dispatcher = JEventDispatcher::getInstance();
                $res = $dispatcher->trigger('onCheckAnswer',$code);
                if ($res[0] === false) {
                    die("Invalid Captcha");
                } else {
                    die("Valid Captcha");
                }

$g_recaptcha_response = $input->get('g-recaptcha-response', '', 'string');
				if (!empty($code)){
                    $response = $code;
                } elseif (!empty($g_recaptcha_response)) {
                    $response  = $g_recaptcha_response;
                } else {
				    $response = '';
                }