Does PHP need to be compiled?

Although php is an interpreted language, it still needs to be compiled. Let me introduce to you which are compiled languages ​​and which are interpreted languages, and what are their advantages and disadvantages.

Compiled language:

1. Use a special compiler (similar to Visual Studio under Windows) to target a specific platform (operating system) A certain high-level language source code is "translated" into machine code (including machine instructions and operands) executed by the platform's hardware at one time, and packaged into an executable program (.exe) format recognized by the platform. This conversion The process is called compilation. The compiled executable program can be separated from the development environment and run independently on a specific platform. After some programs are compiled, they may also need to link other compiled object codes, that is, assemble two or more object code modules to generate the final executable program. In this way, low-level code reuse is achieved.

2. The code of compiled language is compiled once and used repeatedly. In other words, the predecessors planted trees and the descendants enjoyed the shade.

3. C, C, Objective-C, etc. are all compiled languages ​​

Interpreted languages:

1. In the program The source program is pre-compiled into an intermediate language before running, and then the intermediate language is executed by the interpreter

2. Every time a program in an interpreted language is executed, it needs to be compiled once, so the running efficiency of interpreted language programs is generally lower, and it cannot run independently of the interpreter.

3, C#, PHP, Python, Java, etc. are all interpreted languages.

Advantages of compiled languages:

1. One of the biggest advantages of compiled languages ​​is its execution speed. Programs written in C/C run 30%-70% faster than the same programs written in Java.

2. Compiled programs consume less memory than interpreted programs.

Disadvantages:

1. The downside - the compiler is much more difficult to write than the interpreter

2. The compiler is debugging the program Not much help at the time - How many times have you encountered a "null pointer exception" in your C code and spent hours trying to figure out where in the code the error was.

3. Executable compiled code is much larger than the same interpreted code. For example, C/C .exe files are much larger than Java .class files with the same functionality.

4. Compiled programs are platform-specific and therefore platform-dependent.

5. Compiled programs do not support implementing security in the code - for example, a compiled program can access any area of ​​memory and do anything it wants to your PC (mostly Viruses are written using compiled languages)

6. Due to loose security and platform dependency, compiled languages ​​are not suitable for developing Internet or Web-based applications.

Advantages of interpreted languages:

1. Excellent debugging support. It only takes a few minutes for a PHP programmer to locate and fix a "null pointer exception" because the PHP running environment not only indicates the nature of the exception, but also gives the specific line number and function call sequence where the exception occurs (the famous stack trace information). Such convenience is not provided by compiled languages.

2. Interpreters are easier to implement than compilers

3. Excellent platform independence

4. High security-this is urgently needed for Internet applications

5. The size of the intermediate language code is much smaller than the compiled executable code

Disadvantages:

1. It takes up more Memory and CPU resources. This is because, in order to run a program written in an interpreted language, the associated interpreter must first be run. Interpreters are complex, intelligent, resource-intensive programs and they take up a lot of CPU cycles and memory.

2. The running efficiency is much slower than compiled programs. The interpreter does a lot of code optimization and runtime security checks; these extra steps take up more resources and further slow down the application.

The above content is for reference only!

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