What code can a PHP file contain?

The code that a PHP file can contain: 1. PHP code, used to complete various server-side tasks; 2. HTML code, used to define the structure and layout of a web page; 3. CSS code, used to define a web page style; 4. JavaScript code, used to implement various dynamic interaction functions in web pages; 5. SQL code, used to operate the database; 6. The file contains code, which can modularize the code; 7. Third-party libraries and frameworks to quickly build feature-rich applications.

The operating system of this tutorial: Windows10 system, PHP version 8.1.3, DELL G3 computer.

PHP file is a file used to write server-side scripts. It can contain various codes to implement different functions. The following are some common codes that can be included in PHP files:

1. PHP code: PHP files mainly contain PHP code, which can be used to complete various server-side tasks. PHP syntax is simple and flexible, and can implement various common programming structures such as variable definition, conditional judgment, loop, function definition, etc.

2. HTML code: PHP files can contain HTML code to define the structure and layout of the web page. By inserting HTML code in PHP files, static content, styles, and layouts can be rendered in the generated web pages.

3. CSS code: PHP files can contain CSS code to define the style of the web page. By embedding CSS code in the PHP file, you can control the appearance of the generated web page, such as fonts, colors, borders, etc.

4. JavaScript code: PHP files can contain JavaScript code to implement various dynamic interaction functions in web pages. By embedding JavaScript code in PHP files, functions such as form validation, dynamic changes in page elements, and asynchronous requests can be implemented.

5. SQL code: PHP files can contain SQL code to operate the database. By inserting SQL code into the PHP file, various database operations such as database connection, query, and update can be realized.

6. File inclusion code: PHP files can use include and require functions to include other PHP files. In this way, the code can be modularized to improve code reusability and maintainability.

7. Third-party libraries and frameworks: PHP files can contain code for third-party libraries and frameworks. By introducing these libraries and frameworks, you can quickly build feature-rich applications and speed up development.

In actual development, PHP files usually contain the above types of codes to achieve different functions and requirements. Developers can choose appropriate code to include in the PHP file based on specific project needs.

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