How do you create and use sessions in PHP?

Sessions in PHP allow you to store data on the server that can be accessed across multiple pages on a website. This allows you to persist data between requests, such as a user’s login status or shopping cart contents.

To start a new session, use the session_start() function. This function must be called at the beginning of each page that needs to access session data.

Copy code<?php
session_start();

Once a session has been started, you can store data in the $_SESSION superglobal array. This array acts like an associative array, allowing you to store key-value pairs. For example, to store a user’s login status, you could do the following:

Copy code$_SESSION['logged_in'] = true;

To access session data, simply reference the appropriate key in the $_SESSION array. For example:

Copy codeif ($_SESSION['logged_in']) {
    // user is logged in
}

You can also use the session_destroy() function to end a session. This function destroys all data associated with the current session.

Copy codesession_destroy();

Here is a full example of using sessions in PHP to track the number of visits to a website:

Copy code<?php
session_start();

// check if the 'visits' key exists in the session
if (isset($_SESSION['visits'])) {
    // increment the value
    $_SESSION['visits']++;
} else {
    // create the key and set the value to 1
    $_SESSION['visits'] = 1;
}

echo "You have visited this website " . $_SESSION['visits'] . " times.";

In this example, session_start() is called at the beginning of the script to start a new session. The script then checks if the ‘visits’ key exists in the $_SESSION array. If it does, the value is incremented by one. If the key does not exist, it is created and set to 1. The script then echoes the number of visits to the website.

It’s important to note that session data is stored on the server, and a session ID is sent to the client in the form of a cookie. This ID is used to identify the session on the server. If cookies are disabled in the client’s browser, session functionality will not work.