Explore the underlying development principles of PHP: detailed explanation of the compilation, interpretation and execution process

With the rapid development of the Internet, PHP, as a server scripting language, plays an important role in website development and web design. However, there is relatively little understanding of the underlying development principles of PHP. This article will delve into the compilation, interpretation and execution process of PHP to help readers better understand the principles of PHP's underlying development.

First of all, we need to understand the compilation process of PHP. PHP scripts are written in the form of text, but computers can only understand binary codes. Therefore, the compilation process of PHP is the process of converting PHP scripts in text form into binary codes that the computer can understand. During the compilation process, the PHP script will go through a series of steps such as lexical analysis, syntax analysis, and semantic analysis, and finally generate executable binary code.

Lexical analysis is the first step in the compilation process. It divides the text form of the PHP script into individual lexemes. These lexemes include variable names, function names, keywords, etc. Next, syntax analysis combines morphemes into a syntax tree. The syntax tree describes the syntax structure of a PHP script and the relationship between each syntax structure. During the semantic analysis stage, the compiler checks the syntax tree for semantic errors and performs some optimization operations to improve the execution efficiency of the code. Finally, the compiler converts the syntax tree into intermediate code or directly generates target code for execution by the interpreter.

Next, we will understand the interpretation process of PHP. The interpretation process is the next step in PHP compilation, which converts the intermediate code or object code generated by the compilation into machine-executable instructions. During the interpretation process, the PHP interpreter will interpret and execute the code one by one in the order of the code, convert variable assignments, function calls and other operations in the code into underlying machine instructions, and execute these instructions. The interpretation process is dynamic, that is, it needs to be interpreted every time the script is executed. This is one of the reasons why PHP runs relatively slowly.

Finally, we need to understand the execution process of PHP. The execution process occurs after the interpretation process and is the process of executing instructions on the computer hardware. PHP code executed through the interpreter is converted into a series of low-level instructions that are executed directly on the computer hardware. During the execution process, the computer hardware will execute instructions one by one, perform related data operations and calculations, and save the results to memory. The execution process is the final stage of the entire PHP underlying development, and it is the key to converting the code into actual running effects.

To sum up, the underlying development of PHP involves three processes: compilation, interpretation and execution. The compilation process converts PHP scripts in text form into computer-executable binary codes; the interpretation process converts the intermediate code or target code generated by compilation into machine-executable instructions; the execution process executes the instructions on computer hardware to realize the actual code running result. Understanding the principles of PHP's underlying development will help us better understand the operating mechanism of PHP and improve the performance and efficiency of the code. At the same time, it also lays the foundation for us to learn other programming languages.

Although this article has an in-depth discussion of the underlying development principles of PHP, due to space limitations, it is still impossible to introduce all the details in detail. Readers can further learn relevant compilation principles, computer composition principles, operating systems and other knowledge to gain a deeper understanding of the principles and implementation mechanisms of PHP's underlying development. I hope this article can provide readers with some preliminary understanding of PHP's underlying development and inspire further research and exploration of related knowledge.

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