Extra character from WWW text (Compare with www.text not working)

Question

I am programming a login system now on Unity, but I have this weird bug. For some reason when I get the output of the php file, the if statement in the C# file can't see that 'loginreturn' (= AccountDoesntExist) and the string "AccountDoesntExist" are the same. I don't know why but maybe you smart people see the bug and can help me out.

C# Code:

IEnumerator TryLogin(string username, string password)
{
    WWWForm form = new WWWForm();

    form.AddField("username", username);
    form.AddField("password", password);

    WWW loginWWW = new WWW(LoginURL, form);
    yield return loginWWW;

    if (!string.IsNullOrEmpty(loginWWW.error))
    {
        Debug.LogError("Cannot connect to LOGIN servers! Error: " + loginWWW.error);
    }else
    {

        string loginreturn = loginWWW.text;
        Debug.Log(loginWWW.text);
        Debug.Log(loginreturn);

        if (loginreturn == "AccountDoesntExist")
            Debug.Log("WORKS!");

    }
}

PHP Code (which will always return "AccountDoesntExist" because of the way I log in):

<?php

$inputusername = $_REQUEST["username"];
$password = $_REQUEST["password"];

$servername = "localhost";
$username = "chatsystem_accs";
$password = "CENCORED";
$dbname = "chatsystem_accs";

//Create connection
$conn = new mysqli($servername, $username, $password, $dbname);

//Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}
//Connected successfully

$sql = "SELECT `username`, `password` FROM `accounts`";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    while($row = $result->fetch_assoc()) {
        if ($inputusername == $row["username"]) {
            if (password_verify($password, $row["password"])) {
                echo "Success";
            }else {
                echo "UsernameOrPasswordIncorrect";
            }
        }else {
            echo "AccountDoesntExist";
        }
    }
}else {
    echo "AccountDoesntExist";
}

//Close connection
$conn->close();

?>

Answer 1

Very likely a UTF-8 problem. There is an extra data in the received bytes. Convert the received data to UTF-8 before comparing it.

Replace

string loginreturn = loginWWW.text;

with

string loginreturn  = System.Text.Encoding.UTF8.GetString(loginWWW.bytes, 3, loginWWW.bytes.Length - 3);

EDIT:

Did debugging like this:

Debug.Log("Received Length: "+ loginreturn.Length);
Debug.Log("Compare Length: " + "AccountDoesntExist".Length);

and the results were:

Received Length: 19

Compare Length: 18

This is wrong. There is an extra character somewhere. Debugged again with the function below then called it with displayAsChar(loginreturn);

void displayAsChar(string badValue)
{
    char[] values = badValue.ToCharArray();
    for (int i = 0; i < values.Length; i++)
    {
        string tempResult = "Value at index " + i + " is: " + values[i];
        Debug.Log(tempResult);
    }
}

It shows there is an empty character at the end of the character. I thought that was just " " but it wasn't.

I made another function to see what this empty character is:

void showStringAsHex(string badValue)
{
    foreach (char c in badValue)
        Debug.Log("To Unicode: " + ((int)c).ToString("X2"));
}

Bingo. That last character is 0A (Hex) which is also represented as \n. This is used as a line feed.

FIX:

Before doing the compare action, trim the string. This will remove any escape character and empty strings in the beginning and end of the character.

To trim the character, simply add the code below before comparing the string.

loginreturn = loginreturn.Trim();

Why post the debugging process?

The characters might be different for different servers. Posting this will help others troubleshoot and fix this problem for them-selves in the future.