PHP Cookies and Sessions

PHP COOKIES
PHP SESSIONS
PHP include and require Files
2

What is a Cookie?
A cookie is often used to identify a user. A cookie is a small
file that the server embeds on the user's computer. Each time
the same computer requests a page with a browser, it will
send the cookie too. With PHP, you can both create and
retrieve cookie values.
How to Create a Cookie?
 The setcookie() function is used to set a cookie.
 Note: The setcookie() function must appear BEFORE the <html> tag.
Syntax
setcookie(name, value, expire); 3

Example 1
In the example below, we will create a cookie named
"user" and assign the value “John” to it. We also specify
that the cookie should expire after one hour:
<?php
setcookie("user", " John ", time()+3600);
?>
<html>
.....
 Hint… 60*60 4

Example 2
You can also set the expiration time of the cookie in another way. It may
be easier than using seconds.
<?php
$expire=time()+60*60*24*30;
setcookie("user", " 12BSCS ", $expire);
?>
<html>
.....
In the example above the expiration time is set to a month (60 sec * 60
min * 24 hours * 30 days).
5

In the example below, we retrieve the value of the
cookie named "user" and display it on a page:
<?php
// Print a cookie
echo $_COOKIE["user"];
// A way to view all cookies
print_r($_COOKIE);
?>
6

In the following example we use the isset() function to find out if a
cookie has been set:
<html>
<body>
<?php
if (isset($_COOKIE["user"]))
echo "Welcome " . $_COOKIE["user"] . "!<br>";
else
echo "Welcome guest!<br>";
?>
</body>
</html> 7

 A PHP session variable is used to store information about, or change settings for
a user session. Session variables hold information about one single user, and are
available to all pages in one application.
Starting a PHP Session
 Before you can store user information in your PHP session, you must first start
up the session.
 Note: The session_start() function must appear BEFORE the <html> tag:
 <?php session_start(); ?>
<html>
<body>
</body>
</html>
 The code above will register the user's session with the server, allow you to start
saving user information, and assign a UID for that user's session.
8

The correct way to store and retrieve session variables is to use the PHP
$_SESSION variable:
<?php
session_start();
// store session data
$_SESSION['views']=1;
?>
<html>
<body>
<?php
//retrieve session data
echo "Pageviews=". $_SESSION['views'];
?>
</body>
</html>Output: Pageviews=1
9

 In the example below, we create a simple page-views counter. The isset() function
checks if the "views" variable has already been set. If "views" has been set, we can
increment our counter. If "views" doesn't exist, we create a "views" variable, and
set it to 1:
<?php
session_start();
if(isset($_SESSION['views']))
$_SESSION['views']=$_SESSION['views']+1;
else
$_SESSION['views']=1;
echo "Views=". $_SESSION['views'];
?>
10

If you wish to delete some session data, you can use the unset() or the session_destroy()
function.
 The unset() function is used to free the specified session variable:
<?php
session_start();
if(isset($_SESSION['views']))
unset($_SESSION['views']);
?>
 You can also completely destroy the session by calling the session_destroy() function:
<?php
session_destroy();
?>
 Note: session_destroy() will reset your session and you will lose all your stored session data.
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 In PHP, you can insert the content of one PHP file into another PHP file before the
server executes it.
 The include and require statements are used to insert useful codes written in
other files, in the flow of execution.
Syntax
include 'filename';
or
require 'filename';
12

 Assume we have an include file with
some variables defined ("vars.php"):
 <?php
$color='red';
$car='BMW';
?>
 Then the variables can be used in
the calling file:
 <html>
<body>
<h1>Welcome to my home
page.</h1>
<?php include 'vars.php';
echo "I have a $color $car"; // I have a
red BMW
?>
</body>
</html>
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PHP Cookies and Sessions