What are the main computer languages? What are the respective uses?

Computer language Computer language is mainly divided into four categories: - low-level language - high-level language - special-purpose language - scripting language low-level language - machine language, assembly language and symbolic language. - The assembly language source program must be assembled to generate an object file and then executed. High-level languages ??- BASIC (True basic, Qbasic, Virtual Basic), C, C, PASCAL, FORTRAN, intelligent languages ??(LISP, Prolog, CLIPS, OpenCyc, Fazzy), dynamic languages ??(Python, PHP, Ruby, Lua), etc. . - High-level language source programs can be executed in two ways: interpretation and compilation. Usually the latter one is used. The C language we use uses the latter. Specialized language: drawing language in CAD system and database query language in DBMS. 1.1. Machine language Machine language refers to the entire instruction set of a computer. Electronic computers use binary numbers composed of "0" and "1". Binary is the basis of computer language. At the beginning of the invention of computers, people could only use computer language to command the computer to do this or that. In a word, it means writing a series of instruction sequences composed of "0" and "1" for the computer to execute. , this kind of language that computers can understand is machine language. Using machine language is very painful, especially when the program has errors and needs to be modified. Computer language and program are binary files. A piece of machine language becomes an instruction. Instructions are the smallest indivisible functional unit. Moreover, since the instruction system of each computer is often different, if a program executed on one computer wants to be executed on another computer, another program must be programmed, resulting in duplication of work. However, because it uses a language specific to a specific model of computer, its computational efficiency is the highest among all languages. Machine language is the first generation of computer language. 1.2. Assembly language In order to alleviate the pain of using machine language programming, people have made a useful improvement: using some concise English letters and symbol strings to replace the binary string of a specific instruction. For example, use "ADD" to represent addition, "MOV" stands for data transfer, etc. In this way, it is easy for people to read and understand what the program is doing, and error correction and maintenance become convenient. This programming language is called assembly language, which is the second generation of computers. language. However, computers do not recognize these symbols, which requires a special program that is responsible for translating these symbols into machine language of binary numbers. This translation program is called an assembler. Assembly language is also very dependent on machine hardware and has poor portability, but it is still very efficient. Assembly language programs compiled for specific computer hardware can accurately utilize the functions and specialties of computer hardware. The programs are refined and of high quality, so they are still used today. It is a commonly used and powerful software development tool. 1.3. High-level language 1.3.1. Development of high-level language From the initial painful experience of communicating with computers, people realized that a language should be designed that is close to mathematical language or human natural language, while not Depending on the computer hardware, the program can be written on all machines. After hard work, in 1954, FORTRAN, the first high-level language that was completely separated from machine hardware, came out. Over the past 40 years, hundreds of high-level languages ??have appeared, and dozens of them are of great significance and have great influence. The more commonly used ones are FORTRAN, ALGOL, COBOL, BASIC, LISP, SNOBOL, PL/1, Pascal, C, PROLOG, Ada, C, VC, VB, JAVA, etc. Special mention: Before the birth of C language, system software was mainly written in assembly language.

Because assembly language programs rely on computer hardware, their readability and portability are poor; but it is difficult for general high-level languages ??to directly operate computer hardware (this is the advantage of assembly language), so people hope to have a A new language that combines the features of assembly language and high-level language - C language. The development of high-level languages ??has also gone through the process from early languages ??to structured programming languages, and from process-oriented to non-procedural programming languages. Correspondingly, software development has also evolved from the initial closed production of individual manual workshops to industrialized, assembly-line industrial production. Computer Language In the mid-to-late 1960s, there were more and more software and the scale was getting larger and larger. However, the production of software was basically a self-made war. There was a lack of scientific and standardized system planning, testing and evaluation standards. The consequences were that a large number of systems were built and built at a huge cost. The software system that has been developed cannot be used because it contains errors, and even causes huge losses. The software feels increasingly unreliable, so that there is almost no software that is error-free. All this shocked the computer industry greatly and was known as the "software crisis" in history. People realize that the preparation of large programs is different from writing small programs. It should be a new technology and the whole process of software development should be handled like engineering. Programs should be designed so that correctness can be easily ensured and correctness can be easily verified. In 1969, the structured programming method was proposed. In 1970, the first structured programming language, Pascal language, appeared, marking the beginning of the structured programming period. Beginning in the early 1980s, another revolution occurred in software design thinking, and the result was object-oriented programming. Prior to this, high-level languages ??were almost all process-oriented, and the execution of the program was pipeline-like. Before a module was executed, people could not do anything else, nor could they dynamically change the execution direction of the program. This is inconsistent with the way people deal with things every day. For people, they want to deal with one thing when it happens. That is to say, it cannot be process-oriented, but should be oriented to specific application functions, that is, objects. ). The method is the integration of software, just like the integrated circuit of hardware, to produce some general and tightly packaged functional modules, called software integrated blocks, which have nothing to do with specific applications, but can be combined with each other to complete specific application functions. At the same time, it can be reused. For users, they only care about its interface (input volume, output volume) and the functions it can implement. As for how to implement it, that is its internal matter. The user does not need to care at all. C, Visual Basic, and Delphi are typical examples. represent. The next development goal of high-level languages ??is to be application-oriented, that is to say: you only need to tell the program what you want to do, and the program can automatically generate algorithms and automatically process them. This is a non-procedural programming language.