<?PHP

$age = 18;
$username = "ads";
$email = "asd@asd.com";
$name = "asd";
$last_name = "dsa";
$address = "sad";
$phone_number = "123";
$postal_code = "1234";
$country = "das";
$password = "qwe";
$repeat_password = "qwe";

if (is_numeric($age) && !empty($username) && filter_var($email, FILTER_VALIDATE_EMAIL) && !empty($name) && !empty($last_name) && !empty($address) &&
    is_numeric($phone_number) && is_numeric($postal_code) && !empty($country) && !empty($password) && !empty($repeat_password)) {

    if($password === $repeat_password){
        if ($age >= 18){
            //$statement = mysqli_prepare($con, "INSERT INTO users (name, username, age, password, last_name, address, email, phone_number, postal_code, country) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)") or die (mysqli_error($con));
            //mysqli_stmt_bind_param($statement, "ssissssiis", $name, $username, $age, $password, $last_name, $address, $email, $phone_number, $postal_code, $country);
            //mysqli_stmt_execute($statement);
            $response = array("success" => "success", "18" => "nvm", "noMatch" => "nvm", "fill" => "nvm"); // success!
            echo json_encode($response);
        } else {
            $response = array("success" => "nvm", "18" => "18", "noMatch" => "nvm", "fill" => "nvm"); // you are not 18 years old
            echo json_encode($response);

        }

    } else if ($password != $repeat_password) {

            $response = array("success" => "nvm", "18" => "nvm", "noMatch" => "noMatch", "fill" => "nvm"); // Passwords do not match
            echo json_encode($response);

    }
} else {
    $response = array("success" => "nvm", "18" => "nvm", "noMatch" => "nvm", "fill" => "fill"); // Please fill out all fields.
    echo json_encode($response);
}