Design and build

Online Marketing

Other services

PHP For the Absolute Beginner

December 28th, 2007 by admin

This area is intended for everyone new to PHP. It opens with a
series of informal, entertaining tutorials written by Vikram Vaswani,
founder and CEO of Melonfire. These tutorials build on a
previously-published 5-part series which has now been updated and
extended to embrace PHP 5, making parts of it suitable for those of you
who already have worked with PHP 4 in the past.

If you came here to learn about elementary PHP 4 or basic PHP 5, this is for you. Enjoy!

PHP 101 (part 1): Down the Rabbit Hole [July 17, 2004]
An introduction to PHP’s variables and operators.

PHP 101 (part 2): Calling All Operators [July 18, 2004]
The rest of the PHP operators (there are many), and simple form processing.

PHP 101 (PART 3): Looping the Loop [July 19, 2004]
Basic control structures explained.

PHP 101 (PART 4): The Food Factor [July 20, 2004]
Arrays, PHP array functions, and what it all means.

PHP 101 (PART 5): Rank and File [July 21, 2004]
Everything you’re ever likely to need to know about dealing with external files from a PHP script.

PHP 101 (PART 6): Functionally Yours [July 28, 2004]
All about functions, arguments, passing by reference, globals and scope.

PHP 101 (PART 7): The Bear Necessities [August 07, 2004]
A gentle introduction to object oriented programming in PHP 4 and PHP 5.

PHP 101 (PART 8): Databases and Other Animals [August 31, 2004]
All about connecting to a MySQL database from PHP, using the mysql or mysqli extensions.

PHP 101 (PART 9): SQLite My Fire! [September 16, 2004]
Introducing another database: SQLite.

PHP 101 (part 10): A Session In The Cookie Jar [October 3, 2004]
Sessions and cookies – how to keep track of visitors to your site.

PHP 101 (part 11): Sinfully Simple [October 3, 2004]
An introduction to PHP’s easiest method for dealing with XML.

PHP 101 (part 12): Bugging Out [January 30, 2005]
Basic error handling.

PHP 101 (part 13): The Trashman Cometh [February 27, 2005]
A primer in basic security.

PHP 101 (part 14): Going to the Polls [March 8, 2005]
Putting the pieces together – a first Web application.

PHP 101 (part 15): No News is Good News [June 4, 2005]
Creating a simple RSS news aggregator.

by Vikram Vaswani 

del.icio.us Digg Furl Reddit Ask BlinkList blogmarks Blogg-Buzz Google Netscape Shadows Socializer Sphere StumbleUpon Technorati Windows Live Yahoo!

Posted in PHP No Comments »

PHP Login System

December 20th, 2007 by admin

Step 1)

Open a blank document in Notepad and type the following:

Listing 1.1 – form.php

<html>
<head>
<title>Login Form</title>
</head>

<body>
<form method=”post” action=”login.php”>
Username: <input type=”text” name=”username” /><br />
Password: <input type=”password” name=”password” /><br />
<input type=”submit” value=”Login” /><br />
</form>
</body>
</html>

Save this file as form.php.

Here we have set up a simple form that will pass submitted information onto the file login.php.

Step 2)

Now open a second blank document in Notepad and enter the following:

Listing 2.1 – login.php

<?php

session_start();

$passwords = array(”harry” => “dirtyharry”,
“george” => “gorgieboy01″,
“bob” => “bigbobby”,
“jack” => “jackthelad”);

if (!$_POST[”username”] or !$_POST[”password”]) {
echo “Please enter your username and password.”;
exit;
}

if ($_POST[”password”] == $passwords[$_POST[”username”]]) {
echo “Login successful!”;
$_SESSION[”auth_username”] = $_POST[”username”];
}
else {
echo “Login incorrect, please try again.”;
}

?>
<html>
<head>
<title>Login</title>
</head>

<body>
Content in here will only be shown if the username and password supplied are correct.
</body>
</html>

Save this file as login.php.

Notice the php script comes before even the <html>
tags. This ensures that the php is executed before the page gets
rendered, so if the credentials were wrong the offender cannot see
anything protected.

Basically here we tell the browser to start a session to store
usernames and passwords in. We then set up an array called passwords
which contains a list of usernames and respective passwords, from Harry
to Jack.

The next part of the script checks inequality between the submitted
credentials and the known credentials. The exclamation mark means “Does not equal”. If the credentials are indeed false/incorrect the script will display the message “Please enter your username and password.” One the users screen. The exit; function stops the script from continuing as soon as incorrect details are given.

The following section of the script checks for equality inequality
between the submitted credentials and the known credentials. The double
equals checks for equality, whereas a single equals assigns a value to
a variable. If the credentials are correct the script displays “Login successful!” on the users screen. Then a session is started called “auth_username”.
This allows the browser to remember whether or not a user is logged in,
which means that they will not have to login again on a different page.

The final part of the php covers all other eventualities and displays “Login incorrect, please try again.” to the user.

The rest of the page is shown below, between the <html> tags. The message between the <body> tags will not be visible unless the user is logged in.

Step 3)

You have pretty much finished creating a php secure login, but to
illustrate the functionality of sessions, you may want to continue
through Step 3.

Open your third document in notepad and type the following:

Listing 3.1 – auth.inc

<?php
session_start();
if (!isset($_SESSION[”auth_username”])) {
echo “You must be logged in to view this page”;
exit;
}
else {
echo “Hello, you’re logged in!”;
}

?>

auth.inc stores the information related to your
session. You could type the above in every document, but it would
become cumbersome and annoying. By including it using php you only need
type it once and pull it in using the include function, as shown below.

The final script, protected.php, will be an arbitrary page that you wish to secure.

Listing 3.2 – protected.php

<?php

include “auth.inc”;

?>
<html>
<head>
<title>Protected Page </title>
</head>

<body>
Content in here will only be shown if the username and password supplied are correct.
</body>
</html>

This script simply includes auth.inc at the
very beginning. The placement of the script is essential to allowing
the script to function properly. This will run the script typed in Listing 3.1, and will verify the credentials of the user. If they are legitimate the page will continue, displaying everything between the <body> tags, otherwise it will terminate, displaying only “You must be logged in to view this page.”

If you want to protect any further pages you simply need to add the include function at the very top of every page.

P.S. This script is not intended for protection of highly confidential documents, but rather for client extranets etc.

Download the tutorial files.

del.icio.us Digg Furl Reddit Ask BlinkList blogmarks Blogg-Buzz Google Netscape Shadows Socializer Sphere StumbleUpon Technorati Windows Live Yahoo!

Posted in PHP No Comments »
Powered by Doontime