What does session mean in php? how to use?

PHP Session Overview

Session is a more secure way for clients to communicate with the website (server). Once a session is opened, it can be used (maintained) on any page of the website, thus establishing a "dialogue" mechanism between the visitor and the website.

The common online shopping cart is a typical application of session. When we reserve products, we put the selected products into the shopping cart, which actually opens a session for the product. If an order is placed for the selected product, the corresponding information will be written to the database; if no order is ultimately placed, the session will be closed when the user closes the browser or logs out, and the selected product will become invalid.

session session will create a unique session ID for each visitor who opens the session session to identify the user. The session ID may be stored in a cookie on the user's computer, or it may be passed through the URL. The corresponding specific session value will be stored on the server side, which is also the main difference from cookies, and the security is relatively high.

Related topic recommendations: php session (including pictures, texts, videos, cases)

Create session

To create a session, you must first use the session_start() function to open a session, and the system will assign a session ID:

<?php
session_start();
?>

Use the session_register() function to register a session variable, successful Returns TRUE, otherwise returns FALSE.

Syntax:

bool session_register( mixed name [, mixed ...] )

Use the session_register() function to register one or more global session variables under the current session.

Example:

<?php
session_start();
$username = "xiaoli";
session_register("username");
?>

In this example, we register a variable named username with session, and its value is xiaoli.

Read session

PHP’s built-in $_SESSION variable can easily access the set session variable.

Example:

<?php
session_start();
echo "登记的用户名为：".$_SESSION["username"];    //输出 登记的用户名为：xiaoli
?>

Destroy session

You can use the session_unregister() function to log out a single session variable or use session_unset() to log out the entire session session .

Example:

<?php
session_start();
session_unregister("username");    //注销 session 变量
session_unset();                    //注销 session 会话
?>

Another way

You can register the session variable by directly adding the $_SESSION array member:

<?php
session_start();
$_SESSION["username"] = "xiaoli";
?>

If you want to log out this Session variables registered in this way need to use the unset() function:

<?php
session_start();
unset($_SESSION["username"]);
?>

Reading session variables and destroying sessions are the same as the previous methods.

Tips: Unset() cannot be used to destroy the session.

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