Chapter 12 Session Control_PHP Tutorial

Learning points:
1.Cookie application
2.Session session processing

HTTP (Hypertext Transfer Protocol) defines all the rules for transmitting text, graphics, video and all
other data over the World Wide Web (WWW). HTTP is a stateless protocol, meaning that the processing of each request has nothing to do with previous or subsequent
requests. While this simplified implementation made a great contribution to the popularity of HTTP, it can be a bit confusing for developers who want to create complex
Web applications. To solve this problem, there is a way to store a small amount of information (cookie) on the client
machine.
Due to cookie size restrictions, quantity and other reasons, developers have proposed another solution: session will be
processed.

1. Application of Cookies

Set cookie: The setcookie() function can generate a cookie file on the client, which can be saved to the
period, name, value, etc.

Create cookie

<?<span php
</span><span setcookie</span>('name','Lee',<span time</span>()+(7*24*60*60<span ));
</span>?>

Parameter 1: cookie name
Parameter 2: cookie value
Parameter 3: cookie expiration time

Read cookies

<?<span php
</span><span echo</span> <span $_COOKIE</span>['name'<span ];
</span>?>

Delete cookies

<?<span php
</span><span setcookie</span>('name',''<span );
</span><span setcookie</span>('name','Lee',<span time</span>()-1<span );
</span>?>

Restrictions on the use of cookies

1. It must be set before the content of the HTML file is output;
2. Different browsers handle cookies inconsistently, and sometimes incorrect results will occur.
3. The restriction is on the client side. The maximum number of cookies that can be created by a browser is 30, and each cannot
exceed 4KB. The total number of cookies that can be set by each WEB site cannot exceed 20.

2. Session handling

When using session session processing, you must start the session and use session_start() to start the session.

Create session and read session

<?<span php
</span><span session_start</span><span ();
</span><span $_SESSION</span>['name'] = 'Lee'<span ;
</span><span echo</span> <span $_SESSION</span>['name'<span ];
</span>?>

Determine whether the session exists

<?<span php
</span><span session_start</span><span ();
</span><span $_SESSION</span>['name'] = 'Lee'<span ;
</span><span if</span> (<span isset</span>(<span $_SESSION</span>['name'<span ])) {
</span><span echo</span> <span $_SESSION</span>['name'<span ];
}
</span>?>

Delete session

<?<span php
</span><span session_start</span><span ();
</span><span $_SESSION</span>['name'] = 'Lee'<span ;
</span><span unset</span>(<span $_SESSION</span>['name'<span ]);
</span><span echo</span> <span $_SESSION</span>['name'<span ];
</span>?>

Destroy all sessions

<?<span php
</span><span session_start</span><span ();
</span><span $_SESSION</span>['name'] = 'Lee'<span ;
</span><span $_SESSION</span>['name2'] = 'Lee'<span ;
</span><span session_destroy</span><span ();
</span><span echo</span> <span $_SESSION</span>['name'<span ];
</span><span echo</span> <span $_SESSION</span>['name2'<span ];
</span>?>

Note: The article comes from Li Yanhui’s PHP video tutorial. This article is for communication only and may not be used for commercial purposes, otherwise you will be responsible for the consequences.