"C Language" Reading Notes (2) [program and programming language]

In the previous article, I made a plan for myself. To learn the C language well, start now. I thought that when I first came out, I was particularly dependent on Windows. Later I found that my development was often carried out in Linux. How can I not change my mind? I also gradually adapted to Linux. Until half a year ago, I killed the XP system and used ubuntu. Later I found that some people use the MAC system very well, especially the interface, but I think I have been using Ubuntu for a few days, and it is too easy for me to get out of love. Let's continue with my ubuntu. ---- Digress. C development in Ubuntu is quite easy, because I often conduct php development in Ubuntu. -- Linux provides good support for C languages (such as GCC and GDB ). One of my favorite Vim operation tutorials is simple about Vim leveling strategy. It is estimated that you will be able to read it, and you will be able to program vim, especially those animations, which are very interesting. Now, let's get started! If the Mind Map is disconnected from the network, you may not be able to see it. If not, you can see the following picture. Corresponding Mind Map, click to view the big picture

 

Computers dare to ask what computers do in the world? Directly teach coder to set an example. Wiki cloud: A computer, commonly known as a computer, is a machine that processes data based on a series of commands using electronics principles. -- Click here for details. Based on the above knowledge, a computer is an operational machine composed of digital circuits and can only perform operations on numbers (that is, BITs.

Program (Program) -- what is a computer program? We are programmers. If you don't even know the program, you will find a piece of tofu and hit it to death. -- I bumped into it several times and didn't die. I still don't understand why I didn't die! A program refers to a group of commands that indicate the action of each step of a computer or other device with message processing capabilities (the commands here focus on the language level because they are not computer languages and can be considered human languages, then, the compiler converts the language into machine commands. That is to say The program is for people to see, and is eventually converted into instructions for computer execution ). Features: 1. easy to understand. 2. Tell the computer how to complete a computing task. 3. To run on the system, it is necessary to convert it into low-level machine language commands.

What is the meaning of a command? Definition: a command that instructs a computer to perform an operation. Category: input: obtains data from the keyboard, file, or other devices. Output: display data to the screen, store a file, or send data to other devices. Basic operations: perform the most basic mathematical operations (addition, subtraction, multiplication, division) and data access. Test and branch: test a condition and execute different Subsequent commands based on different test results. Loop: repeat a series of operations.

Writing a program is a process of breaking down complex tasks into subtasks, breaking them down into simpler tasks, and breaking them down layer by layer until the above commands can be used to complete the process.

Programming Language Category: low-level and advanced languages. Low-level languages include machine language and assembly language (you must convert them into machine language commands through the assembler before execution ). It is characterized by writing programs directly using computer commands. -- It's hard to figure out how they program. There are more advanced languages, such as C, Java, C #, and C ++. The feature is to write programs using statements. I personally think that the program at this level cannot be considered as an instruction, but it can only be regarded as a language. In the end, the compiled content of the corresponding compiler can be regarded as an instruction, because the machine can recognize it at this time. The compilation and execution process is too long, so I plan to separate a blog article to explain it. To sum up, I don't know what I understand. If there are any mistakes in understanding, I hope you can give me some advice in time so that I can correct them in time. You need to know what is going on, and listen to the next decomposition.

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