<html>
    <body>
    <h1> Welcome. Please enter in a valid username and password.</h1>

        <form action="login2.php" method="post"><input type="hidden" name="ac" value="log">
            UserName: <input type="text" name="username" /> <!--Enter in valid username -->
            Password: <input type="password" name="password" /> <!--Enter in valid password -->
            <input type="submit" value="Login"/> <!--submit username and password -->
        </form>
    </body>
</html>


<?php
$USERS["username1"] = "password1";
$USERS["username2"] = "password2";
$USERS["username3"] = "password3";

function check_logged(){
     global $_SESSION, $USERS;
     if (!array_key_exists($_SESSION["logged"],$USERS)) {
          header("Location: login.php");
     };
};
?>

<?php
session_start(); /// initialize session
include("password.php");
check_logged();
?>
<html>
    <body>
    Welcome, <?php echo $_POST["username"]; ?>
    <form action="view.php" action="LINK">
        <input type="submit" value="View All Records">
    </FORM>
    </br>
    <form action="addform.php" action="LINK">
        <input type="submit" value="Add Records">
    </FORM>
    </br>
    <form action="edit.php" action="LINK">
        <input type="submit" value="Edit Records">
    </FORM>
    </br>
    <form action="delete1.php" action="LINK">
        <input type="submit" value="Delete Records">
    </FORM>
    </br>
    </body>


</html>

<?php
//session_start();
include("password.php");

 if ($_POST["ac"]=="log") { /// do after login form is submitted
     if ($USERS[$_POST["username"]]==$_POST["password"]) { /// check if submitted

          $_SESSION["logged"]=$_POST["username"];
     } else {
          echo 'Incorrect username/password. Please, try again.';
     };
};
if (array_key_exists($_SESSION["logged"],$USERS)) { //// check if user is logged or not
     echo "You are logged in.";//// if user is logged show a message
     echo '<form action="home.php" method="post">';
     echo   '<input type="submit" value="NEXT"/>';
} else { //// if not logged show login form
     echo '<form action="login2.php" method="post"><input type="hidden" name="ac" value="log"> ';
     echo 'Username: <input type="text" name="username" />';
     echo 'Password: <input type="password" name="password" />';
     echo '<input type="submit" value="Login" />';
     echo '</form>';
};

?>