Only variables should be passed by reference in… on line 13 Fail

Question

I\'m practicing building a PHP registration form script for a website. I have done this code, but when I click the submit button I get the notice: Only variables should be p

Answer 1

change this

$stmt->bindParam(':email', $_POST['email']);
$stmt->bindParam(':username', $_POST['username']);
$stmt->bindParam(':password', password_hash($_POST['password'], PASSWORD_BCRYPT));

to this

$email =  $_POST['email'];
$username = $_POST['username'];
$password = password_hash($_POST['password'], PASSWORD_BCRYPT);

$stmt->bindParam(':email', $email);
$stmt->bindParam(':username', $username);
$stmt->bindParam(':password',$password);

the error message is clear though you need to assign those values into variables then pass them

Answer 2

$result->bindParam(':id', $id, PDO::PARAM_INT);

if string, you need write:
$stmt->bindParam(':username', $_POST['username'], PDO::PARAM_STR);