Mysqli登录准备好的声明

Question

Okay, I haved been maked a register system, but when I tried to make the login system it didn't work. When the user log in with the correct username and password its post "You are now logged in", but when I refresh the site, It says I need to login. And I has to ask how I could check the user is logged in exempel If the user logged in so echo this and if not so echo this..

Here is my code:

session_start();
            require 'inc/connect.php';

            if(isset($_POST['name'], $_POST['password'])){
                if(!empty($_POST['name'])){
                    if(!empty($_POST['password'])){


                        $username = $_POST['name'];
                        $password = $_POST['password'];
                        $user = $_SESSION['name'];

                        // KRYPTERING
                        $md5 = md5($password);
                        $sha1 = sha1($md5);
                        $crypt = crypt($sha1, 'st');
                        $md51 = md5($crypt);
                        $sha12 = sha1($md51);
                        $crypt1 = crypt($sha12, 'st');
                        $kode = base64_encode($crypt1);

                        $check = $mysqli->prepare("SELECT username, password FROM user WHERE username=? && password=?");
                        $check->bind_param("ss", $username, $kode);
                        $check->execute();
                        $check->bind_result($username, $kode);
                        $print = $check->fetch();
                        $check->close();

                        if ($print)
                            echo "You are now logged in!";
                        else
                            echo "Username / Password was incorrect!";

                    } else
                        echo "You need something!";
                } else
                    echo "You need something!";
            }

Answer 1

You need to put the username in the session on successful login, to check for it at the top of the page, and redirect to a different when its already set.

session_start();
            require 'inc/connect.php';

if(isset($_SESSION['username']))
{
  //already logged in, redirect
  header('Location: otherpage.php');
  exit;
}

            if(isset($_POST['name'], $_POST['password'])){
                if(!empty($_POST['name'])){
                    if(!empty($_POST['password'])){


                        $username = $_POST['name'];
                        $password = $_POST['password'];
                        $user = $_SESSION['name'];

                        // KRYPTERING
                        $md5 = md5($password);
                        $sha1 = sha1($md5);
                        $crypt = crypt($sha1, 'st');
                        $md51 = md5($crypt);
                        $sha12 = sha1($md51);
                        $crypt1 = crypt($sha12, 'st');
                        $kode = base64_encode($crypt1);

                        $check = $mysqli->prepare("SELECT username, password FROM user WHERE username=? && password=?");
                        $check->bind_param("ss", $username, $kode);
                        $check->execute();
                        $check->bind_result($username, $kode);
                        $print = $check->fetch();
                        $check->close();

                        if ($print)
                        {
                            //redirect to different page for the message
                            //echo "You are now logged in!";
                            $_SESSION['username'] = $username;
                             header('Location: otherpage.php');
                             exit;
                        }
                        else
                            echo "Username / Password was incorrect!";

                    } else
                        echo "You need something!";
                } else
                    echo "You need something!";
            }

Then in the other pages, you'll want something like:

session_start();
if(!isset($_SESSION['username']))
{
  //not logged in, redirect to login form
  header('Location: login_form.php');
  exit;
}