Algorithm refers to the definite and limited steps taken to solve a specific problem[1]。The computer programming language used to express algorithms is called algorithmic language.Algorithmic language is a description tool of algorithms, which is betweenmachine languageA common language between and mathematical language[2]。
Algorithmic language is a design language close to mathematical description, also known ashigh-level language。In essence, algorithmic language is a collection of symbols arranged according to certain rules,CompilerIt is a converter that converts these symbol sets into machine instructions[3]。
Computer language is divided into machine languageassembly languageAnd high-level language.High level language is a kind of artificially designed language. Because it describes specific algorithms, it is also called algorithm language.
Computer has been widely used in various fields of social life and has become a popular modern tool.People write the work that needs to be done by the computer into certain forms of instructions, and store them in the memory inside the computer. When people give commands, it will automatically operate according to the order of instructions.The set of instructions that can be executed continuously is called "program".It can be said that the program is the language of "dialogue" between people and machines, which is also known as "programming language".
At present, there are hundreds of programming languages used in society, such as C, Visual Basic, C++and Java, which are called "high-level languages" of computers.These languages are expressed in natural languages and mathematical languages that are close to people's habits, making it very convenient for people to learn and operate[1]。
Common algorithm languages include BASICFORTRANCOBOL, PASCAL, C, C++, JAVA, etc.
History
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Since the first electronic computer came out in 1946, the work of writing and debugging programs has become inextricably linked with people.The original computer program can only be written in binary machine instruction code.The program written in this way is difficult to understand, difficult to debug, lengthy, and poor in versatility. The original attempt to improve the programming method was to use a relatively easy to remember "mnemonic" to represent binary instructions, and introduce variables into the program, so that the program becomes more readable.At the same time, it also alleviates the difficulties caused by storage arrangements to a certain extent.However, this has not brought about fundamental improvement to the programming work, so the algorithmic language that is closer to the natural language came into being.The algorithm language is easy to learn, and the program written in the algorithm language is easy to read, debug and concise.In addition, the algorithmic language is independent of the computer's instruction system, that is, programs written in algorithmic language can run on any computer equipped with the language compilation system.This makes it easier to learn and use computers.At the same time, it promotes the information exchange between computers.
The first algorithm language is ALGOL. At present, the more popular languages are ALGOL, FORTRAN, COBOL, BASIC, PASCAL and C.Algorithmic languages can be classified according to their own characteristics. ALGOL, FORTAL and other languages are suitable for scientific computing.It belongs to process oriented language.COBOL is the abbreviation of English general business language, which is oriented to data processing.PASCAL, C and other languages emphasize the program structure, and advocate that unconditional transfer statements should be used as little as possible. They are called structured languages.
With the development of artificial intelligence, LISP, PROLOG and other languages have emerged. LISP is also called table processing language, which can be used for symbol processing conveniently.PROLOG takes logical reasoning as its starting point, and its program is composed of a series of rules and facts. At runtime, users ask questions, and computers automatically search for answers.LISP and PROLOG both have the ability to solve intelligent problems[4]。
classification
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In terms of application scope, algorithmic languages are specially designed for various numerical calculations, such as ALGOL60FORTRAN LanguageAnd languages specially designed for data processing and management, such as COBOL, which are applicable to a class of problems and are called universal languages;There are also languages specially designed to deal with a specific problem or adapt to a specific department, such as system simulation language (MIMIC), which are called special languages.
From the perspective of language function, computer language can be divided into process oriented language and problem oriented language.The process oriented language can be used for various computers to calculate various problems. When using this language, it is not only necessary to tell the computer the calculation problems, but also to describe the problem solving method and calculation process;Problem oriented language, you can get the calculation results just by telling the problem to the computer[5]。
characteristic
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Algorithmic language is composed of "keywords" and "expressions" that express different meanings according to certain grammar and semantic rules, thus it is separated from the instruction system.It is a language that is relatively independent of computers. The programs written in it are suitable for different computers.
The algorithm language is close to the natural language and mathematical language that people are accustomed to, so it is easy to learn and has strong versatility[6]。The computer program can be compiled in algorithmic language, as long as you know the morphology, syntax and mathematical formula of various languages and follow certain grammar rules. The compiler does not need to know the internal structure and working principle of the computer[5]。
The computer can not directly recognize the program written by the algorithm language. It can only accept and process binary instructions or data (machine language) composed of 0 and 1 codes[1]Therefore, it needs a translator to translate it into a machine language program before it can be executed.
application
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The purpose of learning algorithmic language is to use language as a tool to design programs that can be run by computers.
Simple program design generally includes the following parts:
(1) Determine the data structure.Determine the data structure for storing data according to the requirements, specified input data and output results in the task statement.
(2) Determine the algorithm.Determine the steps to solve problems and complete tasks according to the data structure where data is stored.
(3) Coding.According to the determined data structure and algorithm, use the selected algorithm language to write program code, input it into the computer and save it on the disk.
(4) Debug the program on the computer.Eliminate grammatical or logical errors caused by negligence;Test the program with all possible input data, so that it can get correct results for all reasonable data, and properly handle unreasonable data.
(5) Organize and document[1]。
Common algorithm languages
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C language
C language program
A general structure oriented programming language.Derived from the B language invented by Ken Thompson.High efficiency, economy and good portability make other languages incomparable.Its characteristics are:
① The character is based on English lowercase letters.
② Provide a large set of operators, and the operators correspond to the shortest machine code.
③ C language is a collection of functions.The parameters of the function are carried out in the way of "value transfer" and "value call".
④ C language provides a complete set of loops, conditional judgments and transfer statements, which is conducive to structured programming.
⑤ C language has rich data types. In addition to basic types, users can customize data types. In addition, pointer types can also be processed as data. Using pointers, you can directly access the absolute address of memory.
⑥ C language can carry out constant definition, macro definition and conditional compilation through preprocessing.
⑦ Many functions of C language, such as screen operation, process control, string processing, I/O storage allocation, can be realized through library functions.
⑧ C language is flexible, transplantable and easy to maintain.
An excellent C program can be compared with assembly language in execution speed[7]。
BASIC
Basic
BASIC (abbreviation of Beginner's All purpose Symbolic Instruction Code) is a literal programming language.The name literally means "beginner's omnidirectional symbolic instruction code". The programming language designed for beginners does not need to go through the procedures of compiling and linking after completion of writing, but can run through the interpreter. However, if it needs to run independently, it still needs to be created into an executable file.
BASIC language was created by professors John G. Kemeny and Thomas E. Kurtz of Dartmouth College in the mid-1960s.Because of its good intention, BASIC language is simple and easy to learn. It soon became popular. Almost all small and micro home computers, even some large computers, provide users with programs written in this language.In terms of microcomputer, BASIC has become one of the main languages of microcomputer because BASIC language can cooperate with the operation function of microcomputer to give full play[8]。
Java
Java
Also known as "Jiawa language", "Java language", a widely used network programming language.It is simple, object-oriented, independent of machine structure, portable, robust, secure, and provides a concurrent mechanism, so it can maximize the use of the network.
The American SUN company officially launched a new generation of programming language in May 1995.It is an object-oriented, cross platform, distributed language, and a world common high-level programming language on the global Internet.The emergence of Java language has brought new vitality and vigor to the development of programming language.Java language not only makes Web pages lifelike through browsers, but also affects many aspects and changes them as a new computing concept.
c++
C++is the inheritance of C language. It can not only carry out procedural programming of C language, but also carry outAbstract data typeIt can also carry out object-oriented programming characterized by inheritance and polymorphism.While C++is good at object-oriented programming, it can also carry out process based programming, so C++can adapt to the size of the problem.
