What is POEM? I tried googling and find "code poetry" but i dont think it's the right answer.Secondly, you said, i dont "else" the result of checking for existing users in the "register"function.I have done that in your code.Maybe, it escaped you.You also said, you have to see the form. The form is actually already included in the code.You just have to scroll down the page when you access the pastebin.I have updated the pastebin to see my current script. By the way, this is what is happening now. Am getting an error of "registration failed" when i try to register new user but the form data get inserted into the database table. I also get a success message of "login successful" but am not directed to the page specified. What is going on under hood causing these?

Emmanuel Obeng

What is POEM?

Prepare Once, Execute Mostly. It's an archaic term from 1990's RDMS, but one that fits the prepare/execute model. When using PDO the only 'real' time to use bindParam is when doing POEM or truly over-the-top worried about typecasting.

An example of POEM would be if you had an array of usernames and passwords you wanted to insert.

$newUsers = [
    'jake' => 'gumbo',
    'jimbo' => 'martyr',
    'jenna' => 'bimbo'
];

$stmt = $db->prepare('
    INSERT INTO users (
        username, password
    ) VALUES (
        :username, :password
    )
');
$stmt->bindParam(':username', $username);
$stmt->bindParam(':password', $password);

foreach ($newUsers as $username => $password) {
    $password = password_hash($password);
    $stmt->execute();
}

Prepare once, bind once, so that inside the loop you keep all the processing to a minimum. "POEM". A lot of batch imports and transfers can be done quickly and easily using the model where quite often the only thing inside the loop ends up the ->execute();

i dont "else" the result of checking for existing users in the "register"function.I have done that in your code.Maybe, it escaped you

You didn't do it for either of your first two checks. If I entered a username that didn't match up with your first check or an invalid e-mail, it would still plod on to try and run the query to check if the user exists. The same for your login where you can enter an 'invalid' username, but it will still run the query after $result is set.

The form is actually already included in the code.

I'm not seeing it here.... wait, ok. I see it if I view the page in firefox. Gah, this is why I don't like things like pastebin -- when they can't even make pages that work right in Chromium or Vivaldi ... Ok, NOW I see the form. :/

Am getting an error of "registration failed" when i try to register new user

Notice my rewrite has the response of FALSE. Hence where you have this:

$user = register($username,$email,$password);
if ($user) {
        $success = "registration successful";
}else {
        $error = "registration failed,try again";
}

It should be more like this:

if (!($error = register($username,$email,$password)))
    $success = "registration successful";

... and where you have this:

$isLoggedIn = login($username,$password);
if ($isLoggedIn) {
                $success = "login successful";
        }else {
                $error = "an error occured,try again";
        }  

it would/should be like this:

if (!($error = login($username,$password)))
    $success = "login successful";

Basically by returning false on SUCCESS and the error message on failure, we simplify the logic greatly. Just assign the result to $error, and if not $error we must have been successful. That's why it's evaluating backwards the way you have it in the pastebin right now.

To that end, I probably wouldn't even have a $success variable, further down where you have sections like this:

if (isset($success)) {
        echo $success;
}

if (isset($error)) {
        echo $error;
}

I would just:

echo $error ?: 'Login Successful';

That way up top where you run the login function all you have to do is:

$error = login($username,$password);

With no extra 'if' statements even needed in that part of the code.

Simplify, simplify, simplify.

-- edit -- oh, as to your markup, what's with the DIV for nothing, classes for nothing, etc, etc.. using some sort of front-end framework nonsense? Also, if you're using HTML5 it's just 'required' you don't need to ="required" unless you go XHTML (where it doesn't even EXIST) -- and placeholder is not a label and "enter username" is not a guide as to WHAT to enter format-wise. placeholder="non-space characters only" would be proper use of the placeholder attribute.