unable to convert to lowercase - not working

Question

I have the below code on my page but I want to to work for logging in even if username and password was entered in lowercase, I ave looked online and the answer answer seems to suggest strtolower would work, but it doesn't work for me, can anyone take a look?

thanks for any assistance!

<?php
    $error = "";
    if(isset($_POST['username'],$_POST['password'])){
        $user = array(
                        "user" => "Demo",
                        "pass"=>"Demo"          
                );
        $username = strtolower($_POST['username']);
        $pass = strtolower($_POST['password']);
        if($username == $user['user'] && $pass == $user['pass']){
            session_start();
            $_SESSION['simple_login'] = $username;
            echo '{"error":0}';
        }else{
            echo '{"error":1}';
        }
        exit();
    }
?>

Answer 1

Although this is one way to do it, you probably shouldn't be doing it this way, this isn't really secure. Why should the username/password be case insensitive?

<?php
    $error = "";
    if(isset($_POST['username'],$_POST['password'])){
        $user = array(
                        "user" => strtolower("Demo"),
                        "pass"=> strtolower("Demo")          
                );
        $username = strtolower($_POST['username']);
        $pass = strtolower($_POST['password']);
        if($username == $user['user'] && $pass == $user['pass']){
            session_start();
            $_SESSION['simple_login'] = $username;
            echo '{"error":0}';
        }else{
            echo '{"error":1}';
        }
        exit();
    }
?>