php is an interpreted language. PHP is a simple, object-oriented, interpreted, robust, secure, very high-performance, architecture-independent, portable, dynamic scripting language; the PHP interpreter will interpret PHP code as The opcode is then handed over to the Zend engine for execution.
The operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer
php is an interpreted language. Each platform has a corresponding php interpreter version, which means that the binary code of the target platform is compiled for different platforms; the php interpreter will interpret the PHP code into opcode and then hand it over to the Zend engine for execution.
php (Hypertext Preprocessor), that is, hypertext preprocessor;
is a server-side HTML scripting language, which is a simple, object-oriented, Interpreted, robust, safe, extremely high-performance, architecture-independent, portable, and dynamic scripting language. It is a multi-purpose scripting language widely used in Open Source that is particularly suitable for web development and can be embedded in HTML. Its syntax is close to C and easy to learn.
Is php a compiled language or an analytical language?
Translation: Translating high-level language into machine language that can be recognized by computers is called translation. Translation method: compilation, interpretation;
Compilation: Before a program written in a compiled language is executed, a special compilation process is required to compile the program into a machine language file, such as an .exe file, which only needs to be compiled once. That’s it;
Explanation: Interpreted languages do not need to be compiled and will only be translated when the program is running. For example, PHP language requires a special interpreter fastcgi to directly execute the code. Each statement is directly It will only be translated when executed; such an interpreted language must be translated every time it is executed;
The following is the code execution process in other languages:
java: Code----> Through the compiler, it is translated into java bytecode (bytecode) ----> When run, it is translated into machine code through the interpreter
c#: Code ----> Compiled into Microsoft intermediate code - --->Translated into machine code via clr
php (version 4.0): code---->Translated into op code intermediate code---->Use Zend virtual machine to execute Opcode during execution phase , compiled into machine code
In fact, the conversion process of most programming languages from source files to executable codes is source code-intermediate code-final code (machine code )form. The difference between the compiled type and the interpreted type is that this process only needs to be executed once or may be executed multiple times for the same source file in at least the case. For Java, as its slogan "compile once, execute anywhere", the source file is compiled into intermediate code (class file) at one time, and then the process of converting it into machine code on different machines is automatically completed by the JVM, and no program is needed. The staff is worried. Under normal circumstances, PHP will execute this conversion process every time it is accessed. apc only "caches" the intermediate code. Pay attention to the word "cache", which indicates that it may still be generated multiple times for a source file due to the passage of time (cache expiration).
APC: alternative php cache, is a php opcode cache, the goal is to provide a free, open and sound framework for caching and optimizing php intermediate code; if apc is installed, compilation can be omitted , no need to compile into op code, directly obtain the cache, and then interpret it into machine code.
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