PHP session session processing function, session session

Home

Backend Development

PHP Tutorial

PHP session session processing function, session session_PHP tutorial

WBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWB

Jul 12, 2016 am 08:50 AM

phpsessionfunction

PHP session session processing function, session session

PHP Session variable

When you run an application, you open it, make changes, and then close it. It's a lot like a session. The computer knows who you are. It knows when you start the application and when it terminates it. But on the Internet, there's a problem: the server doesn't know who you are and what you do, and that's because HTTP addresses don't maintain state.

PHP session solves this problem by storing user information on the server for subsequent use (such as user name, purchased items, etc.). However, session information is temporary and will be deleted after the user leaves the site. If you need to store information permanently, you can store the data in a database.

Session works by creating a unique id (UID) for each visitor and storing variables based on this UID. The UID is stored in a cookie or passed through the URL.

1. Start conversation

Before saving information to the session, you must first open the session. PHP provides the session_start() function to start or continue a session. Definition:

1 bool session_start( void )

The call is as follows:

<&#63;php session_start();&#63;>
 <html>
 <body></body>
 </html>

Note:

(1) The session_start() function must be located before the tag, that is, the function must be called before any output. Often when writing a program, an extra space or carriage return is accidentally entered. In this case, An error will be reported. Special attention should be paid to this. (I have been tricked)

(2) The session_start() function will return TRUE regardless of whether the session is successfully created, so using any exception handling will not work.

(3) You can also enable the configuration instruction session.auto_start so that you do not have to execute this function, but in this case, a session will be started or continued when each php page is executed.

2. Store or read session

The correct way to store and read session variables is to use PHP's S ESSION variable. SESSION variable. _SESSION is a global parameter provided by PHP and is specially used to store and read sessions. (Note that the key names of associative arrays are consistent with the naming rules of ordinary variables)

When storing a session, you can assign it directly.

$_SESSION['season'] = 'Autumn';

The above sets a session element with the key name "season" and its value is "autumn". When reading, it is just like calling a normal array element.

The following two code snippets show how to store and read a session element.

This is the session1.php file:

 <&#63;php
 /**
  * Created by PhpStorm.
  * User: yuxiu
  * Date: //
  * Time: :
  */
 if(isset($_POST['submit'])){
   session_start();                //开始建立一个会话
   $_SESSION['season'] = $_POST['season'];    //存储会话数据
   header("Location: session.php");      //应特别注意header()里的格式问题
 }
 &#63;>
 <b>存储会话</b>
 <hr/>
 选择需要设置的数据：
 <form name="form" method="post" action="" id="form" >
   <select name="season" id="season_select" >
     <option value="春天">春天</option>
     <option value="夏天">夏天</option>
     <option value="秋天">秋天</option>
     <option value="冬天">冬天</option>
   </select>
   <br/>
   <br/>
   <br/>
  <input type="submit" name="submit" value="submit"/>
 </form>

This is the session2.php file:

 <&#63;php
 /**
  * Created by PhpStorm.
  * User: yuxiu
  * Date: //
  * Time: :
  */
 session_start();  //建立或者继续一个会话
 $season = $_SESSION['season'];    //读取会话数据
 echo "<b>读取会话</b><br/><br/>";
 switch ($season) {
   case '春天';
     echo '现在是绿意盎然的春天！';
     break;
   case '夏天';
     echo '现在是热情四溢的夏天！';
     break;
   case '秋天';
     echo '现在是丰收果实的秋天!';
     break;
   case '冬天';
     echo '现在是白雪皑皑的冬天!';
     break;
   default ;
     echo '对不起，会话中没有数据 或者 不存在该对话 ！';
 }
 &#63;>

In session1.php, first use session_start() to create a session, then use array assignment to store the submitted seasonal data, and finally use the header() function to jump directly to the beginning. In the session2.php file, the session_start() function is also needed to continue a session and use the session array to call session information.

3. Destroy session

When the session is no longer used, it needs to be destroyed manually. Although PHP has the function of automatically destroying the session, this will make the program less efficient. You can use the unset() function or session_destroy() function.

<&#63;php
 unset($_SESSION['season']);
&#63;>

Or:

<&#63;php
 session_destroy();   //注意，使用这个函数将重置session数组，即失去所有的已经储存的session数据
&#63;>

Statement

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

PHP's Purpose: Building Dynamic WebsitesApr 15, 2025 am 12:18 AM

PHP is used to build dynamic websites, and its core functions include: 1. Generate dynamic content and generate web pages in real time by connecting with the database; 2. Process user interaction and form submissions, verify inputs and respond to operations; 3. Manage sessions and user authentication to provide a personalized experience; 4. Optimize performance and follow best practices to improve website efficiency and security.

PHP: Handling Databases and Server-Side LogicApr 15, 2025 am 12:15 AM

PHP uses MySQLi and PDO extensions to interact in database operations and server-side logic processing, and processes server-side logic through functions such as session management. 1) Use MySQLi or PDO to connect to the database and execute SQL queries. 2) Handle HTTP requests and user status through session management and other functions. 3) Use transactions to ensure the atomicity of database operations. 4) Prevent SQL injection, use exception handling and closing connections for debugging. 5) Optimize performance through indexing and cache, write highly readable code and perform error handling.

How do you prevent SQL Injection in PHP? (Prepared statements, PDO)Apr 15, 2025 am 12:15 AM

Using preprocessing statements and PDO in PHP can effectively prevent SQL injection attacks. 1) Use PDO to connect to the database and set the error mode. 2) Create preprocessing statements through the prepare method and pass data using placeholders and execute methods. 3) Process query results and ensure the security and performance of the code.

PHP and Python: Code Examples and ComparisonApr 15, 2025 am 12:07 AM

PHP and Python have their own advantages and disadvantages, and the choice depends on project needs and personal preferences. 1.PHP is suitable for rapid development and maintenance of large-scale web applications. 2. Python dominates the field of data science and machine learning.

PHP in Action: Real-World Examples and ApplicationsApr 14, 2025 am 12:19 AM

PHP is widely used in e-commerce, content management systems and API development. 1) E-commerce: used for shopping cart function and payment processing. 2) Content management system: used for dynamic content generation and user management. 3) API development: used for RESTful API development and API security. Through performance optimization and best practices, the efficiency and maintainability of PHP applications are improved.

PHP: Creating Interactive Web Content with EaseApr 14, 2025 am 12:15 AM

PHP makes it easy to create interactive web content. 1) Dynamically generate content by embedding HTML and display it in real time based on user input or database data. 2) Process form submission and generate dynamic output to ensure that htmlspecialchars is used to prevent XSS. 3) Use MySQL to create a user registration system, and use password_hash and preprocessing statements to enhance security. Mastering these techniques will improve the efficiency of web development.

PHP and Python: Comparing Two Popular Programming LanguagesApr 14, 2025 am 12:13 AM

PHP and Python each have their own advantages, and choose according to project requirements. 1.PHP is suitable for web development, especially for rapid development and maintenance of websites. 2. Python is suitable for data science, machine learning and artificial intelligence, with concise syntax and suitable for beginners.

The Enduring Relevance of PHP: Is It Still Alive?Apr 14, 2025 am 12:12 AM

PHP is still dynamic and still occupies an important position in the field of modern programming. 1) PHP's simplicity and powerful community support make it widely used in web development; 2) Its flexibility and stability make it outstanding in handling web forms, database operations and file processing; 3) PHP is constantly evolving and optimizing, suitable for beginners and experienced developers.

See all articles