Jednoduche prihlasenie pomocou SESSION

<?php
$users = array(
  "user1" => "heslo1",
  "user2" => "heslo2",
  "user3" => "heslo3",
  "user4" => "heslo4"
);

session_start();
if (isset($_POST["user"]) && isset($_POST["pass"])) {
  foreach ($users as $login => $pass) {
    if ($_POST["user"] == $login && $_POST["pass"] == $pass) {
      $_SESSION["logged"] = true;
      $_SESSION["user"] = $_POST["user"];
    }
  }
}





if ($_SESSION["logged"]) {echo "Vitaj ".$_SESSION["user"].". Dlho si sa neukázal";}
else {
  echo "<form action='".$_SERVER["PHP_SELF"]."' method='post' style='margin-top: 20px;'><fieldset><table>";
  echo "<tr><td>Login:</td><td><input type='text' name='user' /></td></tr>";
  echo "<tr><td>Heslo:</td><td><input type='password' name='pass' /></td></tr>";
  echo "</table><input type='submit' class='submit' value='Prihlásiť sa' /></fieldset></form>";
}
?>