Session in PHP


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Create Session in PHP

Session is used to store and pass information from one page to another temporarily (until user close the website). In case of cookie, the information are store in user computer but in case of session information is not stored on the users computer.

session in php

Why use session in PHP

When you work with any application, you open it, do some changes, and then you close it. This is much like a Session. The computer knows who you are. It knows when you start the application and when you end. But on the internet there is one problem; the web server does not know who you are or what you do, because the HTTP address doesn't maintain state.

Session variables solve this problem by storing user information to be used across multiple pages (e.g. username, favorite color, etc). By default, session variables last until the user closes the browser. So; Session variables hold information about one single user, and are available to all pages in one application.

Start PHP Session

A session is started with the session_start() function. Session variables are set with the PHP global variable: $_SESSION.

session_start() function in PHP

PHP session_start() function is used to start the session. It starts a new or resumes existing session. It returns existing session if session is created already. If session is not available, it creates and returns new session.

Syntax

bool session_start ( void )  

Example

session_start ()  

Here we create a new web page with name myapp1.php

Start Session

<?php
// Start the session
session_start();
?>

<!DOCTYPE html>
<html>
<body>
<?php

// Set session variables
$_SESSION["favcolor"] = "green";
$_SESSION["favanimal"] = "cat";
echo "Session variables are set.";

?>
<body>
<html>

Note: The session_start() function must be declare top of your php page, Before any HTML tags.

Get PHP Session Variable Values

Now we create new page myapp2.php for get previous page session information. All session variable values are stored in the global $_SESSION variable

Get PHP Session Variable Values

<?php
session_start();
?>

<!DOCTYPE html>
<html>
<body>

<?php

// Echo session variables that were set on previous page
echo "Favorite color is " . $_SESSION["favcolor"] . ".<br>";
echo "Favorite animal is " . $_SESSION["favanimal"] . ".";

?>

<body>
<html>

Another way to get session

Get PHP Session Variable Values

<?php
session_start();
?>

<!DOCTYPE html>
<html>
<body>

<?php
print_r($_SESSION);
?>

<body>
<html>

The code above will get an error like this

	
Message: Value must be 1 or below

Modify a PHP Session Variable

To change a session variable, just overwrite it:

Modify a PHP Session Variable

<?php
session_start();
?>

<!DOCTYPE html>
<html>
<body>

<?php

// to change a session variable, just overwrite it 
$_SESSION["favcolor"] = "yellow";
print_r($_SESSION);

?>

<body>
<html>

Destroy Session in PHP

To remove all global session variables and destroy the session, use session_unset() and session_destroy() method.

Destroy Session

<?php
session_start();
?>

<!DOCTYPE html>
<html>
<body>
<?php
// remove all session variables
session_unset(); 

// destroy the session 
session_destroy(); 
?>
<body>
<html>

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