Session

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Table Of Contents

• [[#What is a PHP Session?

  What is a PHP Session?]]

• [[#Start session

  Start session]]

• [[#Set session variables

  Set session variables]]

• [[#Get PHP session values

  Get PHP session values]]

• [[#Remove all session variables

  Remove all session variables]]

• [[#Destroy the session

  Destroy the session]]

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What is a PHP Session?

• A session is a way to store information (in variables) to be used across multiple pages.Unlike a cookie, the information is not stored on the users computer.

• When you work with an 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.

Tip: If you need a permanent storage, you may want to store the data in a database.

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Start session

1. start it manually

   session_start();  
   

2. edit php.ini file

   sed -i 's/session.auto_start = 0/session.auto_start = 1/'  php.ini
   

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

Note The session_start() function must be the very first thing in your document. Before any HTML tags.

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Set session variables

$_SESSION["favcolor"] = "yellow";

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Get PHP session values

print_r($_SESSION); // print all the values 
echo "Favorite color is " . $_SESSION["favcolor"] . ".<br>";

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• How does it work? How does it know it’s me?

Most sessions set a user-key on the user’s computer that looks something like this: 765487cf34ert8dede5a562e4f3a7e12. Then, when a session is opened on another page, it scans the computer for a user-key. If there is a match, it accesses that session, if not, it starts a new session.

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Remove all session variables

session_unset();

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Destroy the session

session_destroy();

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