WebDev: Simple Login Tutorial Using PHP. (DB Less Version)

Hi Friends,
Today I would like to say how to create a login system using PHP, without using Databases.

We need these files:
1. index.php - Index file, where your protected content and login form is there.
2. login.php - Login Form.
3. logout.php - Script for logging out.

Code: index.php


<?php
session_start(); // Initiate the session
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
    "https://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="https://www.w3.org/1999/xhtml">
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
    <title>Welcome</title>
    <style type="text/css">
        * {font-family: Tahoma; font-size: 12px;}
        a {color: #0000ff; text-decoration: none;}
        a:hover {color: #ff0000;}
    </style>
</head>

<body>
    <?php
    if(isset($_SESSION["logged"])) // Check if the user had logged in.
        echo 'Welcome! [url=logout.php]Logout[/url].';
    else // User did not log in.
        echo 'Please [url=login.php]Login[/url].';
    ?>
</body>
</html>

Code: login.php


<?php
session_start(); // Initiate the session.
$err = false; // Set an Error Flag.
if(count($_POST))
    if(isset($_POST["username"], $_POST["password"])) // See if the user has entered both username and password.
        if($_POST["username"]=="Admin" && $_POST["password"]=="LetMeIn") // Check for the correctness of both username and password.
        {
            $_SESSION["logged"] = true; // Set the session as authenticated.
            header('Location: index.php'); // Redirect the user to the home page.
            die(); // Stop the script.
        }
        else
            $err = true; // Username or password is wrong! Set error flag.
    else
        $err = true; // User didn't provide both username and password.
else
    $err = false; // User logs in for the first time.
?><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "https://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="https://www.w3.org/1999/xhtml">
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
    <title>Login</title>
    <style type="text/css">
        * {font-family: Tahoma; font-size: 12px;}
        label {display: inline-block; width: 75px; margin: 5px 0px; padding: 5px;}
        input {border: 0px; border-bottom: 1px solid #cccccc; width: 100px; margin: 5px 0px; padding: 3px;}
        form {text-align: center;}
    </style>
</head>

<body>
    <?php if($err) echo '[b]Invalid Login! Provide all values![/b]<br />'; // If the error flag is set, display error message. ?>
    <form method="post">
        <div><label for="username">Username:</label> <input type="text" name="username" /></div>
        <div><label for="password">Password:</label> <input type="password" name="password" /></div>
        <div><input type="submit" value="Login!" /></div>
    </form>
</body>
</html>

Code: index.php


<?php
    session_start(); // Initiate the session
    session_destroy(); // Destroy the session
    header('Location: index.php'); // Redirect the user to the home page
?>

Now keep all the files in the same folder... Ready to execute?

Execution
I personally recommend USB Web Server for fast food execution. Download it at #-Link-Snipped-#
Now copy the three files in the Root folder of USB Web Server and open the port #-Link-Snipped-# in your favourite browser and enjoy. I have also attached the set of files, which I used with this post. 😀

All the coding is documented. Even then if you have any queries, do shoot them out in the replies. 😀

Download the files: #-Link-Snipped-#