Simple and easy to understand, how Session works (_PHP tutorial
Let’s take a look at how Session works. I wonder if you know that identity authentication is achieved through cookies. First, a unique cookie is generated as a sign of user identity and registered in the database. The cookie passed by the user is then compared with the cookie registered in the database to determine the user's identity.
Session works the same way.
First, PHP generates a unique string for the user who created the session to identify the user's session. This string is generally called Session Id. Then "sess" + Session Id is the file name (for example, if a Session ID is 111, then the file name is sess_111), create a file in the server's file system, and save the variable names and values of the global variables defined by the user in the Session in the file. Then the Session Id is saved in the user's file system as a cookie named PHPSession.
Then, when the user connects to the server again to access a PHP script, PHP gets the Session Id of the session where the user is from the PEESession cookie sent by the user, and saves the session information file from the server's file system based on the Session Id. Finally, the value of the global variable set by the user during the last connection is read from this file.
Therefore, we can see that the working principle of Session is the same as the working principle of identity authentication introduced in the previous section. The only difference is that Session saves the information in the server's file system, and we save the information in the database. Of course, the advantage of using Session is that data saving and retrieval are automatically completed by PHP, but if you use Cookie directly, you need to save and obtain data yourself.
Session uses the identity mark function of Cookie to save the information that users need to save when browsing the website on the server. In this way, Session not only overcomes the shortcomings of the HTTP protocol, but also prevents information leakage, and is convenient for programmers to use. It is a very good solution. However, the Session function is only supported by PHP4, and PHP3 does not support Session. Therefore, readers who use PHP3 to build websites can only use cookies directly.

What’s still popular is the ease of use, flexibility and a strong ecosystem. 1) Ease of use and simple syntax make it the first choice for beginners. 2) Closely integrated with web development, excellent interaction with HTTP requests and database. 3) The huge ecosystem provides a wealth of tools and libraries. 4) Active community and open source nature adapts them to new needs and technology trends.

PHP and Python are both high-level programming languages that are widely used in web development, data processing and automation tasks. 1.PHP is often used to build dynamic websites and content management systems, while Python is often used to build web frameworks and data science. 2.PHP uses echo to output content, Python uses print. 3. Both support object-oriented programming, but the syntax and keywords are different. 4. PHP supports weak type conversion, while Python is more stringent. 5. PHP performance optimization includes using OPcache and asynchronous programming, while Python uses cProfile and asynchronous programming.

PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.

PHP originated in 1994 and was developed by RasmusLerdorf. It was originally used to track website visitors and gradually evolved into a server-side scripting language and was widely used in web development. Python was developed by Guidovan Rossum in the late 1980s and was first released in 1991. It emphasizes code readability and simplicity, and is suitable for scientific computing, data analysis and other fields.

PHP is suitable for web development and rapid prototyping, and Python is suitable for data science and machine learning. 1.PHP is used for dynamic web development, with simple syntax and suitable for rapid development. 2. Python has concise syntax, is suitable for multiple fields, and has a strong library ecosystem.

PHP remains important in the modernization process because it supports a large number of websites and applications and adapts to development needs through frameworks. 1.PHP7 improves performance and introduces new features. 2. Modern frameworks such as Laravel, Symfony and CodeIgniter simplify development and improve code quality. 3. Performance optimization and best practices further improve application efficiency.

PHPhassignificantlyimpactedwebdevelopmentandextendsbeyondit.1)ItpowersmajorplatformslikeWordPressandexcelsindatabaseinteractions.2)PHP'sadaptabilityallowsittoscaleforlargeapplicationsusingframeworkslikeLaravel.3)Beyondweb,PHPisusedincommand-linescrip

PHP type prompts to improve code quality and readability. 1) Scalar type tips: Since PHP7.0, basic data types are allowed to be specified in function parameters, such as int, float, etc. 2) Return type prompt: Ensure the consistency of the function return value type. 3) Union type prompt: Since PHP8.0, multiple types are allowed to be specified in function parameters or return values. 4) Nullable type prompt: Allows to include null values and handle functions that may return null values.


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