发布请求C＃之后获取回声值（WebClient UploadValues）

Question

I use Xamarin (C#) and PHP (with MySqli to connect to my database) to send data via POST request. I have a webclient where I send post request to PHP file for account creation and everything work fine but I need the PHP to echo a response after it received data (User already exist, user doen't exist... etc) and the C# receive it. Actually, my PHP print the response on his code via echo but I don't know how to check the state of the page as reaction after it received my data.

                            using (WebClient client = new WebClient())
                        {
                            var data = new NameValueCollection();
                            data.Add("userid", userid.ToString());
                            data.Add("password", password);

                            byte[] response = client.UploadValues(Url, data);
                            string rep = client.DownloadString("http://xxxx.fr/CreateProfile.php");
                            Toast.MakeText(this, rep, ToastLength.Short).Show();
                        }

Actually my request is sent and ONLY AFTER, it download the code so I have the error message "Student doesn't exist" everytime. Otherwise, when I try to use it via a simple form it works. So the error is not in the PHP because the request is well executed on my database but I just ask for the page's code too late an without any parameter..

Here is my PHP code:

if ($data === "404"){
    echo "Student doesn't exist";
    }

else{
$checkIfExist= "SELECT name FROM users WHERE id = $user_id";
    if($result = $conn->query($checkIfExist)) {
        $row_cnt = $result->num_rows;
              } 

    if ($row_cnt > 0){
        echo "User already exist.";
    }

    else{
        echo"New user";
    }

So I want to know if I can get the echo returned when I send the values using WebClient or if I need to use something else like HttpClient or HttpRequest...

Answer 1

Solution was so simple, thanks to Jason

use Encoding.ASCII.GetString(response)