Lecture
High-level languages are used in machine-independent programming systems. Such programming systems are easier to use than machine-oriented systems.
High-level programming languages are divided into procedural-oriented, problem-oriented and object-oriented.
Procedural-oriented languages are used to record procedures or algorithms for processing information on each specific set of tasks. These include:
a) the language Fortran (Fortran), whose name comes from the words Formulae Translation - "the transformation of formulas." Fortran is one of the oldest high-level programming languages. The duration of its existence and use can be explained by the simplicity of the structure of a given language;
b) the Basic language, which stands for Beginner’s All-purpose Symbolic Instruction Code, which means “multi-purpose symbolic learning code for beginners,” developed in 1964 as a language for teaching programming;
c) language C (C), used since the 1970s. as a system programming language specifically for writing UNIX OS. In the 1980s on the basis of the C language, the C ++ language was developed, practically including the C language and supplemented by means of object-oriented programming;
d) the language Pascal (Pascal), which is named after the French scientist B. Pascal, began to be applied from 1968-1971. N. Wirth. When creating Pascal was used for teaching programming, but over time it became widely used for developing software in professional programming.
Problem-oriented languages are used to solve entire classes of new problems that have arisen in connection with the constant expansion of the field of application of computing equipment:
a) Lisp language (Lisp - List Information Symbol Processing), which was invented in 1962 by J. McCarthy. Initially, it was used as a tool for working with character strings. Lisp is used in expert systems, analytical computing systems, and so on;
b) Prolog (Prolog - Programming in Logic), used for logical programming in artificial intelligence systems.
Object-oriented languages are still evolving. Most of these languages are versions of procedural and problem languages, but programming using the languages of this group is more intuitive and simple. The most frequently used *** languages include:
a) Visual Basic (~ Basic);
b) Delphi (~ Pascal);
c) Visual Fortran (~ Fortran);
r) C ++ (~ C);
e) Prolog ++ (~ Prolog).
An algorithm written in a programming language is called a program. The algorithm must include all situations that may arise in the process of solving a complex task.
Programming is a theoretical and practical activity related to the creation of a program.
The program is the result of intellectual work, which is characterized by creativity, individuality of developers. At the same time, programming also involves routine work that can and should have strict rules for implementation and conform to standards. Programming is based on a complex of scientific disciplines aimed at researching, developing and applying methods and tools for developing programs (special tools for creating programs).
The 20s of the XIX century. Pre-recording the order of actions of the machine on the punch card for the subsequent automatic implementation of the calculations - the program (proposed by H. Babbage). Ada Lovelace has theoretically developed some sequence control techniques that are still in use.
40th years of XX century. Creating programs based on machine instruction coding (Grace Murray Hopper).
50s-60s. The role of programming in machine codes is decreasing, procedural high-level programming languages appear (FORTRAN, ALGOL). Translators are used to translate commands into machine codes.
Mid 60s. Creating a specialized programming language consisting of simple words of the English language (BASIC), attempts to create a universal language (PL / 1, ALGOL-68).
The beginning of the 70s. The development of the idea of ALGOLA on the structuring of the development of algorithms, the creation by N. Wirth of the Pascal language. The creation of the ADA language, designed to create and maintain long-term large software systems, allowing the possibility of parallel processing, process control in real time, etc.
1972 (The first version of the C language). The emergence of a language combining the features of a high-level language with a machine-oriented language, which allows the programmer to all machine resources.
For many years, software was built on the basis of operational and procedural languages (Assemblers, Fortran, Basic, Pascal, Ada, C). With the evolution of programming languages, other fundamentally new approaches to creating programs, non-procedural programming: object-oriented programming (C ++, Delphi, Visual Basic) and declarative programming have become widespread. Declarative languages are divided into logical (Prolog) and functional (Lisp). Currently, languages developed in a managed environment that provide high reliability and security of the created programs (Java, C #, VB.net) are developed.
Programming languages are formal languages specially created for human communication with a computer. Each programming language, as well as "natural language" (Russian, English, etc.) has:
When describing a language and using it, language concepts are used.
A concept is a certain syntactic construction and the properties of program objects or data processing determined by it.
The interaction of syntax and semantic rules defines certain concepts of a language, for example, operators, identifiers, variables, functions and procedures, modules , etc. Unlike natural languages, the rules of grammar and semantics for programming languages, as well as for all formal languages, must be explicitly stated unambiguously and clearly.
Programming languages that mimic natural languages that have large integrated systems ***, focused on the solution of applied substantive problems, are called high- level languages .
A programming language in which elements are introduced that allow description of the task in a visual, easily perceived form, simplifying and automating the programming process, control structures and data structures.
The HPLANs reflect concepts that are natural to humans, and not the architecture of the computing system. Therefore, the program compiled in the JSPU is first transmitted by the computer itself to the machine language (low level), and then executed.
The alphabet may consist of letters, numbers, mathematical symbols, and even so-called keywords, for example:
According to the syntax rules, source sentences are built from the source symbols, usually called operators, for example: if x 1, use the formula y = x - 1.
Thus, high-level programming languages are machine-independent and require the use of appropriate translation software (translators) to represent the program in the language of the machine in which it will be executed.
Fortran. The first compiled language created by Jim Backus in the 50s. A huge number of libraries were created for this language, ranging from static complexes to satellite control packages, therefore Fortran continues to be actively used in many organizations, and now work is underway on the next Fortran standard F2k, which appeared in 2000. There is a standard version of Fortran HPF (High Performance Fortran) for parallel super computers with multiple processors.
Cobol. This is a compiled language for use in the economic field and solving business problems, developed in the early 60s. It is distinguished by its great verbosity - its operators look like ordinary English phrases. In Kobol, very powerful tools for working with large amounts of data stored on various external media were implemented. Many different applications have been created in this language that are being actively exploited today. Suffice it to say that the Cobol programmers receive the highest salary in the United States.
Algol. Compiled language, created in 1960. It was intended to replace FORTRAN, but due to its more complex structure it was not widely used. In 1968, the Algol68 version was created, which in its capabilities is ahead of many programming languages today, but due to the lack of sufficiently efficient computers, it was not possible to create good compilers in a timely manner.
Pascal. The Pascal language, created in the late 70s by Nikolaus Wirth, the founder of many modern programming ideas, is a lot like Algol, but it tightens a number of requirements for the program structure and there are opportunities to successfully use it when creating large projects.
Basic. For this language, there are compilers and interpreters, and in popularity it is ranked first in the world. It was created in the late 60s as a textbook and is very easy to learn.
C. This language was created in the Bell laboratory and was not originally considered as massive. It was planned to replace the assembler, to be able to create equally effective and compact programs, and at the same time not to depend on the specific type of processor.
C ++. This is an object-oriented extension of the C language, created by Bjarn Straustrup in 1980. Many new powerful features, which have dramatically increased the productivity of programmers, have been superimposed on a certain low level inherited from C, resulting in the creation of complex and reliable programs that required a high level of professionalism from developers.
Java. This language was created by Sun in the early 60s based on C ++. It is designed to simplify the development of C ++ based applications by excluding all low-level capabilities from it. But the main feature of this language is compilation not into machine code, but into platform-independent byte code. This bytecode can be executed using the JVM Java Virtual Machine (Java Virtyal Machine) virtual machine, versions of which are created today for any platforms. Due to the presence of Java-machines, Java programs can be transferred not only at the source level, but also at the level of regular byte-code, therefore, Java is the second most popular language in the world after BASIC.
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Informatics
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