Understand the underlying development principles of PHP: introduction to basic knowledge and concepts

Understand the underlying development principles of PHP: Introduction to basic knowledge and concepts

As a PHP developer, it is very important to understand the underlying development principles of PHP. Because of this, this article will introduce the basic knowledge and concepts of PHP's underlying development to help readers better understand and apply PHP.

1. What is PHP?

PHP (full name: Hypertext Preprocessor) is an open source scripting language mainly used for Web development. It can be embedded into HTML documents, interpreted and executed by the server, and generate dynamic page content. PHP code can be run on the server side, generating HTML code and sending it to the client browser, which greatly enhances the interactivity and dynamics of Web applications.

2. The underlying development principle of PHP

1. Interpreted language
   PHP is an interpreted language that does not need to be compiled into machine code, but is generated by the program when the program is running. The parser interprets and executes line by line. This makes it easier to modify and run PHP code, but it also causes a certain performance loss.
2. PHP Engine
   The PHP engine is responsible for parsing and executing PHP code. Common PHP engines include Zend Engine and HHVM (HipHop Virtual Machine). Zend Engine is the officially recommended engine of PHP, implemented in C language, and includes components such as lexical analyzer, syntax analyzer, compiler and executor.
3. HTTP request processing
   When a user accesses a PHP page in a browser, the browser will send an HTTP request to the server. The server receives the request through a web server such as Apache and Nginx, and then hands the request to the PHP engine for processing. PHP will parse the request parameters, process the request, and finally generate the response content and return it to the client browser.
4. Variables and data types
   PHP supports various data types, such as integer, floating point, string, Boolean, array, object, etc. Variables do not have strict data type declarations in PHP and can be dynamically assigned as needed. But at the same time, it also brings certain type safety hazards to development, and developers need to ensure the correct use of variables.
5. Memory Management
   PHP’s memory management is handled by Zend Engine. When PHP executes a script, it will apply for a memory space to store variables and other data. When variables are no longer used, Zend Engine will promptly reclaim memory. PHP uses a garbage collection mechanism to manage memory, but because it is an interpreted language, the efficiency of garbage collection is relatively low.

3. Application scenarios of PHP underlying development

1. PHP extension development
   PHP provides a wealth of extension interfaces for developers to use, and they can develop their own applications according to application needs. Defined PHP extension. Developing PHP extensions can improve system performance, add functional modules, etc. Extension development requires familiarity with C language and underlying knowledge of PHP.
2. PHP Performance Optimization
   Understanding the underlying principles of PHP can help developers better optimize performance. Improve the performance of PHP applications by reducing memory usage, optimizing SQL queries, caching pages, etc. An in-depth understanding of the underlying principles of PHP can help developers locate and solve performance problems.
3. PHP Framework Development
   Many PHP frameworks, such as Laravel, Symfony, CodeIgniter, etc., are developed based on the bottom layer of PHP. Understanding the underlying principles of PHP can better understand the working principles and internal mechanisms of these frameworks, so that you can better use and extend the framework.

4. Methods of learning the underlying development of PHP

1. Reading the source code
   An important way to deeply understand the underlying development principles of PHP is to read the PHP source code. By reading the source code, you can understand the internal structure and underlying implementation mechanism of PHP. PHP source code is available on the official website.
2. Learn C language
   Although PHP is a high-level language, the underlying development of PHP usually requires the use of C language. Learning C language can help developers better understand and modify the underlying source code of PHP.
3. Reference documentation and tutorials
   PHP officially provides detailed documentation and tutorials, including various features of PHP and knowledge related to underlying development. By reading documents and tutorials, you can systematically learn the relevant knowledge of PHP's underlying development.

Summary:

This article introduces the basic knowledge and concepts of PHP underlying development. Understanding the underlying development principles of PHP is very important for PHP developers, which can help developers better understand and apply PHP. I hope that through the introduction of this article, readers will have a deeper understanding of the underlying development of PHP and be able to use it flexibly in practice.

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