PHP Cookies and Sessions
Cookies and Sessions are used to manage user state and data across different pages of a website.
1. Cookies
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.
Setting a Cookie
Use setcookie() before any HTML output.
// Name, Value, Expiration (86400 = 1 day), Path
setcookie("user", "John Doe", time() + (86400 * 30), "/");Retrieving a Cookie
Use the $_COOKIE superglobal.
if(!isset($_COOKIE["user"])) {
echo "Cookie named 'user' is not set!";
} else {
echo "Value is: " . $_COOKIE["user"];
}2. Sessions
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, but on the server.
Starting a Session
Use session_start() at the very beginning of your script.
<?php
session_start();
?>Storing and Retrieving Session Variables
Use the $_SESSION superglobal.
// Set session variables
$_SESSION["favcolor"] = "green";
$_SESSION["favanimal"] = "cat";
// Get session variables
echo "Favorite color is " . $_SESSION["favcolor"];Destroying a Session
To remove all global session variables and destroy the session, use session_unset() and session_destroy().
session_unset();
session_destroy();