PHP session is used to store information on the server. The data will be available to all pages in one application.
A session creates a file in a temporary directory on the server where registered session variables and their values are stored.
Starting a PHP Session
Before use session variables, you must first start the session using the session_start() function.
The Function session_start() should be in starting, and you can't send anything to the browser before it.
Example:
<?php
session_start();
?>
<html>
<body>
</body>
</html> When you start a session a unique session id (PHPSESSID) for each visitor/user is created. You can access the session id using the PHP session_id() function or predefined constant PHPSESSID.
Storing a Session Variable
$_SESSION[] is an associative array, which is used to store information is a session. These variables can be accessed during the lifetime of a session.
Example:
<?php
session_start();
// store session data
$_SESSION["username"] = "nikita";
$_SESSION["email"] = "[email protected]";
//retrieve session data
echo $_SESSION["username"];
echo "<br>";
echo $_SESSION["email"];
?> Destroying a Session
A complete PHP session can be terminated by using session_destroy() function, which does not require any arguments.
Example:
<?php
session_start();
session_destroy();
?> If you wish to delete a single session variable, then you can use unset() function.
Example:
<?php
session_start();
if(isset($_SESSION[username]))
unset($_SESSION[username]);
?>