Online PHP editor | output for aXool

@ 2014-02-03T14:39:51Z

<?php
if ($_SESSION['logged'] == true) {
    echo 'Здравейте ' . $username . '<br><br><a href="logout.php">Изход</a>';
} else {
    if ($_POST) {
        $username = trim($_POST['username']);
        $password = $_POST[password];
        $get = "SELECT * FROM `users` WHERE username=" . $username . "";
        if ($result = mysqli_query($con, $get)) {
            while ($row = mysqli_fetch_assoc($result)) {
                $hash = $row['password'];

                if (password_verify($password, $hash)) {
                    echo 'Valid';
                } else {
                    echo 'Invalid';
                }
            }
        }
        if ($chek > 0) {
            $_SESSION['logged'] = $username;
            echo "Вие влязохте успешно.";
            echo '<meta http-equiv="refresh" content="1;url=index.php"> ';
        } else {
            echo "Грешно потребителско име или парола.";
        }
    }
}
?>

Output for 8.3.0 - 8.3.6: Warning: Undefined global variable $_SESSION in /in/aXool on line 2 Warning: Trying to access array offset on null in /in/aXool on line 2
Output for 8.1.0 - 8.1.28, 8.2.0 - 8.2.18: Warning: Undefined global variable $_SESSION in /in/aXool on line 2 Warning: Trying to access array offset on value of type null in /in/aXool on line 2
Output for 8.0.0 - 8.0.30: Warning: Undefined variable $_SESSION in /in/aXool on line 2 Warning: Trying to access array offset on value of type null in /in/aXool on line 2
Output for 7.4.0 - 7.4.25, 7.4.27 - 7.4.33: Notice: Undefined variable: _SESSION in /in/aXool on line 2 Notice: Trying to access array offset on value of type null in /in/aXool on line 2
Output for 7.3.32 - 7.3.33, 7.4.26
Output for 5.0.4 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.31: Notice: Undefined variable: _SESSION in /in/aXool on line 2
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.3: Notice: Undefined variable: _SESSION in /in/aXool on line 2

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