username

<?php
session_start();
if(isset($_SESSION['username'])) {
    echo "You're already registered as $_SESSION[username].";
}
elseif($_SERVER['REQUEST_METHOD'] == 'POST') {
    if(!empty(trim($_POST['username']))
    && !empty(trim($_POST['email'])))
    {
        $uname = htmlentities($_POST['username']);
        $email = htmlentities($_POST['email']);
        $_SESSION['username'] = $uname;
        echo "Thanks for registering! <br />".
        "Username: $uname <br />".
        "Email: $email <br />";
    }
    else {
        echo "Please fill out both fields! <br />";
    }
}
else {
?>
<form action="test.php?username=overwritten" method="post">
<label for="username">Username:</label>
<input type="text" name="username" />
<label for="email">Email:</label>
<input type="text" name="email" />
<input type="submit" value="Register!" />
</form>
<?php
}
// End else statement