How Does PHP\'s Execution Process Unfold?

How Does PHP Execution Unfold?

The prevailing misconception that PHP scripts undergo parsing and subsequent interpretation and execution is incorrect. In fact, PHP has been a compiled language since its 4.0 version.

PHP's Zend engine serves as a central component in the execution process. During the first phase, PHP source code is parsed and converted into Zend opcodes, akin to Java bytecodes. These opcodes represent instructions that are stored in memory.

The second phase of the Zend engine's execution involves executing the generated opcodes. This process culminates in the desired output.

In the case of included files, they are first processed independently, resulting in their own sets of opcodes. Subsequently, these opcodes are merged with the opcodes of the main PHP script.

For further insights into PHP's compilation mechanism, refer to http://www.phpclasses.org/blog/post/117-PHP-compiler-performance.html.

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