computer programming
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Computer programming is the process of performing a particular
computation
computation
(or more generally, accomplishing a specific
computing Computing is any goal-oriented activity requiring, benefiting from, or creating computer, computing machinery. It includes the study and experimentation of algorithmic processes, and development of both computer hardware , hardware and software. ...

computing
result), usually by designing and building an executable computer program. Programming involves tasks such as analysis, generating
algorithm
algorithm
s, profiling algorithms' accuracy and resource consumption, and the implementation of algorithms (usually in a chosen programming language, commonly referred to as coding). The source code of a program is written in one or more languages that are intelligible to
programmer
programmer
s, rather than machine code, which is directly executed by the
central processing unit
central processing unit
. The purpose of programming is to find a sequence of instructions that will automate the performance of a task (which can be as complex as an
operating system
operating system
) on a
computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as Computer program, pr ...

computer
, often for solving a given problem. Proficient programming thus usually requires expertise in several different subjects, including knowledge of the application domain, specialized algorithms, and formal
logic
logic
. Tasks accompanying and related to programming include testing, debugging, source code maintenance, implementation of build systems, and management of derived artifacts, such as the machine code of computer programs. These might be considered part of the programming process, but often the term '' software development'' is used for this larger process with the term ''programming'', ''implementation'', or ''coding'' reserved for the actual writing of code. '' Software engineering'' combines
engineering
engineering
techniques with software development practices. ''
Reverse engineering
Reverse engineering
'' is a related process used by designers, analysts, and programmers to understand an existing program and re-implement its function.


History

Programmable devices have existed for centuries. As early as the 9th century, a programmable music sequencer was invented by the Persian Banu Musa brothers, who described an automated mechanical
flute
flute
player in the '' Book of Ingenious Devices''. In 1206, the Arab engineer Al-Jazari invented a programmable drum machine where a musical mechanical
automaton An automaton (; plural: automata or automatons) is a relatively self-operating machine, or control mechanism designed to automatically follow a sequence of operations, or respond to predetermined instructions.Automaton – Definition and More ...
could be made to play different rhythms and drum patterns, via pegs and cams. Noel Sharkey (2007)
A 13th Century Programmable Robot
University of Sheffield The University of Sheffield (informally Sheffield University or TUOS) is a public university, public research university in Sheffield, South Yorkshire, England. Its history traces back to the foundation of Sheffield Medical School in 1828, Firth C ...
In 1801, the
Jacquard loom The Jacquard machine () is a device fitted to a loom that simplifies the process of manufacturing textiles with such complex patterns as brocade, damask and matelassé. The resulting ensemble of the loom and Jacquard machine is then called a Jac ...
could produce entirely different weaves by changing the "program" – a series of
pasteboard Card stock, also called cover stock and pasteboard, is paper that is thicker and more durable than normal writing and printing paper, but thinner and more flexible than other forms of paperboard. Card stock is often used for business cards, p ...
cards with holes punched in them.
Code-breaking Cryptanalysis (from the Greek language, Greek ''kryptós'', "hidden", and ''analýein'', "to analyze") refers to the process of analyzing information systems in order to understand hidden aspects of the systems. Cryptanalysis is used to breach C ...
algorithms have also existed for centuries. In the 9th century, the Arab mathematician
Al-Kindi Abū Yūsuf Yaʻqūb ibn ʼIsḥāq aṣ-Ṣabbāḥ al-Kindī (; ar, أبو يوسف يعقوب بن إسحاق الصبّاح الكندي; la, Alkindus; c. 801–873 AD) was an Arab The Arabs (singular: Arab; singular ar, عَر ...
described a
cryptographic Cryptography, or cryptology (from grc, , translit=kryptós "hidden, secret"; and ''graphein'', "to write", or ''-logy, -logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of ...
algorithm for deciphering encrypted code, in ''A Manuscript on Deciphering Cryptographic Messages''. He gave the first description of
cryptanalysis Cryptanalysis (from the Greek language, Greek ''kryptós'', "hidden", and ''analýein'', "to analyze") refers to the process of analyzing information systems in order to understand hidden aspects of the systems. Cryptanalysis is used to breach C ...
by
frequency analysis In cryptanalysis, frequency analysis (also known as counting letters) is the study of the letter frequencies, frequency of letters or groups of letters in a ciphertext. The method is used as an aid to breaking classical ciphers. Frequency anal ...
, the earliest code-breaking algorithm. The first computer program is generally dated to 1843, when mathematician
Ada Lovelace Augusta Ada King, Countess of Lovelace (''née'' Byron; 10 December 1815 – 27 November 1852) was an English mathematician and writer, chiefly known for her work on Charles Babbage's proposed mechanical general-purpose computer, the Ana ...
published an
algorithm
algorithm
to calculate a sequence of
Bernoulli numbers In mathematics Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in ...
, intended to be carried out by
Charles Babbage Charles Babbage (; 26 December 1791 – 18 October 1871) was an English polymath. A mathematician, philosopher, inventor and mechanical engineer, Babbage originated the concept of a digital programmable computer. Babbage is considered ...
's
Analytical Engine The Analytical Engine was a proposed mechanical general-purpose computer designed by English mathematician and computer pioneer Charles Babbage. It was first described in 1837 as the successor to Babbage's difference engine, which was a des ...
. In the 1880s
Herman Hollerith Herman Hollerith (February 29, 1860 – November 17, 1929) was a German-American statistician, inventor, and businessman who developed an electromechanical tabulating machine for punched cards to assist in summarizing information and, later, in ...
invented the concept of storing ''data'' in machine-readable form. Later a control panel (plug board) added to his 1906 Type I Tabulator allowed it to be programmed for different jobs, and by the late 1940s,
unit record equipment Starting at the end of the nineteenth century, well before the advent of electronic computers, data processing was performed using Electromechanics, electromechanical machines collectively referred to as unit record equipment, electric accounting ...
such as the IBM 602 and IBM 604, were programmed by control panels in a similar way, as were the first
electronic computer A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as C ...
s. However, with the concept of the
stored-program computer A stored-program computer is a computer that stores Instruction (computer science), program instructions in electronically or optically accessible memory. This contrasts with systems that stored the program instructions with plugboards or simila ...
introduced in 1949, both programs and data were stored and manipulated in the same way in
computer memory In computing, memory is a device or system that is used to store information for immediate use in a computer or related computer hardware and Digital data, digital Electronics, electronic devices. The term ''memory'' is often synonymous with th ...
.


Machine language

Machine code In computer programming Computer programming is the process of performing a particular computation (or more generally, accomplishing a specific computing result), usually by designing and building an executable computer program. Programm ...
was the language of early programs, written in the
instruction set In computer science Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to Applied sci ...
of the particular machine, often in
binary Binary may refer to: Science and technology Mathematics * Binary number A binary number is a number expressed in the base-2 numeral system or binary numeral system, a method of mathematical expression which uses only two symbols: typical ...
notation.
Assembly language In computer programming, assembly language (or assembler language, or symbolic machine code), often referred to simply as Assembly and commonly abbreviated as ASM or asm, is any low-level programming language with a very strong correspondence be ...
s were soon developed that let the programmer specify instruction in a text format (e.g., ADD X, TOTAL), with abbreviations for each operation code and meaningful names for specifying addresses. However, because an assembly language is little more than a different notation for a machine language, two machines with different instruction sets also have different assembly languages.


Compiler languages

High-level languages made the process of developing a program simpler and more understandable, and less bound to the underlying hardware. The first compiler related tool, the A-0 System, was developed in 1952 by
Grace Hopper Grace Brewster Hopper (; December 9, 1906 – January 1, 1992) was an American computer scientist, mathematician, and United States Navy Rear admiral (United States), rear admiral. One of the first programmers of the Harvard Mark I, Harvard Mar ...
, who also coined the term 'compiler'. Maurice V. Wilkes. 1968. Computers Then and Now. Journal of the Association for Computing Machinery, 15(1):1–7, January. p. 3 (a comment in brackets added by editor), "(I do not think that the term compiler was then 953in general use, although it had in fact been introduced by Grace Hopper.)"
The World's First COBOL Compilers
FORTRAN, the first widely used high-level language to have a functional implementation, came out in 1957, and many other languages were soon developed—in particular,
COBOL COBOL (; an acronym An acronym is a word or name formed from the initial components of a longer name or phrase. Acronyms are usually formed from the initial letters of words, as in ''NATO'' (''North Atlantic Treaty Organization''), but so ...
aimed at commercial data processing, and
Lisp A lisp is a speech impairment in which a person misarticulates sibilants (, , , , , , , ). These misarticulations often result in unclear speech. Types * A frontal lisp occurs when the tongue is placed anterior to the target. Interdental lisping ...
for computer research. These compiled languages allow the programmer to write programs in terms that are syntactically richer, and more capable of abstracting the code, making it easy to target for varying machine instruction sets via compilation declarations and heuristics. Compilers harnessed the power of computers to make programming easier by allowing programmers to specify calculations by entering a formula using
infix notation Infix notation is the notation commonly used in arithmetic Arithmetic () is an elementary part of mathematics Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spac ...
.


Source code entry

Programs were mostly entered using punched cards or
paper tape file:PaperTapes-5and8Hole.jpg, Five- and eight-hole punched paper tape file:Harwell-dekatron-witch-10.jpg, Paper tape reader on the Harwell computer with a small piece of five-hole tape connected in a circle – creating a physical program loop ...
. By the late 1960s,
data storage device Data storage is the recording (storing) of information (data) in a storage medium. Handwriting, Phonograph record, phonographic recording, magnetic tape, and optical discs are all examples of storage media. Biological molecules such as RNA a ...
s and
computer terminal A computer terminal is an electronic or electromechanical computer hardware, hardware device that can be used for entering data into, and transcribing data from, a computer or a computing system. The Teleprinter, teletype was an example of an e ...
s became inexpensive enough that programs could be created by typing directly into the computers.
Text editor A text editor is a type of computer program A computer program is a sequence or set of instructions in a programming language for a computer to Execution (computing), execute. Computer programs are one component of software, which also inclu ...
s were also developed that allowed changes and corrections to be made much more easily than with
punched cards A punched card (also punch card or punched-card) is a piece of stiff paper that holds digital data represented by the presence or absence of holes in predefined positions. Punched cards were once common in data processing applications or to di ...
.


Modern programming


Quality requirements

Whatever the approach to development may be, the final program must satisfy some fundamental properties. The following properties are among the most important: *
Reliability Reliability, reliable, or unreliable may refer to: Science, technology, and mathematics Computing * Data reliability (disambiguation), a property of some disk arrays in computer storage * High availability * Reliability (computer networking), a ...
: how often the results of a program are correct. This depends on conceptual correctness of algorithms and minimization of programming mistakes, such as mistakes in resource management (e.g.,
buffer overflow In information security and computer programming, programming, a buffer overflow, or buffer overrun, is an anomaly in software, anomaly whereby a computer program, program, while writing Data (computing), data to a Data buffer, buffer, overruns th ...
s and
race condition A race condition or race hazard is the condition of an electronics, software, or other system where the system's substantive behavior is Sequential logic, dependent on the sequence or timing of other uncontrollable events. It becomes a software ...
s) and logic errors (such as division by zero or off-by-one errors). *
Robustness Robustness is the property of being strong and healthy in constitution. When it is transposed into a system, it refers to the ability of tolerating perturbations that might affect the system’s functional body. In the same line ''robustness'' ca ...
: how well a program anticipates problems due to errors (not bugs). This includes situations such as incorrect, inappropriate or corrupt data, unavailability of needed resources such as memory, operating system services, and network connections, user error, and unexpected power outages. *
Usability Usability can be described as the capacity of a system to provide a condition for its users to perform the tasks safely, effectively, and efficiently while enjoying the experience. In software engineering, usability is the degree to which a soft ...
: the
ergonomics Human factors and ergonomics (commonly referred to as human factors) is the application of psychological and physiological principles to the engineering and design of products, processes, and systems. Four primary goals of human factors learnin ...
of a program: the ease with which a person can use the program for its intended purpose or in some cases even unanticipated purposes. Such issues can make or break its success even regardless of other issues. This involves a wide range of textual, graphical, and sometimes hardware elements that improve the clarity, intuitiveness, cohesiveness and completeness of a program's user interface. * Portability: the range of
computer hardware Computer hardware includes the physical parts of a computer, such as the computer case, case, central processing unit (CPU), Random-access memory, random access memory (RAM), Computer monitor, monitor, Computer mouse, mouse, Computer keyboard, ...
and platforms on which the source code of a program can be
compiled In computing, a compiler is a computer program that Translator (computing), translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primarily ...
/ interpreted and run. This depends on differences in the programming facilities provided by the different platforms, including hardware and operating system resources, expected behavior of the hardware and operating system, and availability of platform-specific compilers (and sometimes libraries) for the language of the source code. *
Maintainability In engineering, maintainability is the ease with which a product can be maintained to: * correct defects or their cause, * Repairability, Repair or replace faulty or worn-out components without having to replace still working parts, * prevent unex ...
: the ease with which a program can be modified by its present or future developers in order to make improvements or to customize, fix bugs and security holes, or adapt it to new environments. Good practices during initial development make the difference in this regard. This quality may not be directly apparent to the end user but it can significantly affect the fate of a program over the long term. *
Efficiency Efficiency is the often measurable ability to avoid wasting materials, energy, efforts, money, and time in doing something or in producing a desired result. In a more general sense, it is the ability to do things well, successfully, and without ...
/
performance A performance is an act of staging or presenting a play, concert, or other form of entertainment. It is also defined as the action or process of carrying out or accomplishing an action, task, or function. Management science In the work place ...
: Measure of system resources a program consumes (processor time, memory space, slow devices such as disks, network bandwidth and to some extent even user interaction): the less, the better. This also includes careful management of resources, for example cleaning up temporary files and eliminating
memory leak In computer science Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to Applied scie ...
s. This is often discussed under the shadow of a chosen programming language. Although the language certainly affects performance, even slower languages, such as
Python Python may refer to: Snakes * Pythonidae The Pythonidae, commonly known as pythons, are a Family (biology), family of Venomous snake, nonvenomous snakes found in Africa, Asia, and Australia. Among its members are some of the largest snakes i ...
, can execute programs instantly from a human perspective. Speed, resource usage, and performance are important for programs that bottleneck the system, but efficient use of programmer time is also important and is related to cost: more hardware may be cheaper.


Readability of source code

In computer programming,
readability Readability is the ease with which a reader can understand a written text Writing is a medium of human communication which involves the representation of a language through a system of physically Epigraphy, inscribed, Printing press, mec ...
refers to the ease with which a human reader can comprehend the purpose,
control flow In computer science, control flow (or flow of control) is the order in which individual statements, instructions or function calls of an imperative program are executed or evaluated. The emphasis on explicit control flow distinguishes an ' ...
, and operation of source code. It affects the aspects of quality above, including portability, usability and most importantly maintainability. Readability is important because programmers spend the majority of their time reading, trying to understand, reusing and modifying existing source code, rather than writing new source code. Unreadable code often leads to bugs, inefficiencies, and duplicated code. A study found that a few simple readability transformations made code shorter and drastically reduced the time to understand it. Following a consistent
programming style Programming style, also known as code style, is a set of rules or guidelines used when writing the source code for a computer program. It is often claimed that following a particular programming style will help programmers read and understand sour ...
often helps readability. However, readability is more than just programming style. Many factors, having little or nothing to do with the ability of the computer to efficiently compile and execute the code, contribute to readability. Some of these factors include: *Different
indent style In computer programming, an indentation style is a convention governing the Indentation (typesetting), indentation of Block (programming), blocks of code to convey program structure. This article largely addresses the free-form languages, such a ...
s (whitespace) * Comments *
Decomposition Decomposition or rot is the process by which dead organic substances are broken down into simpler organic or inorganic matter such as carbon dioxide, water, simple sugars and mineral salts. The process is a part of the nutrient cycle and is e ...
*
Naming conventions A naming convention is a convention (generally agreed scheme) for naming things. Conventions differ in their intents, which may include to: * Allow useful information to be deduced from the names based on regularities. For instance, in Manhatta ...
for objects (such as variables, classes, functions, procedures, etc.) The
presentation A presentation conveys information from a speaker to an audience. Presentations are typically demonstrations, introduction, lecture, or speech meant to inform, persuade, inspire, motivate, build goodwill, or present a new idea/product. Presen ...
aspects of this (such as indents, line breaks, color highlighting, and so on) are often handled by the
source code editor A source-code editor is a text editor program designed specifically for editing source code of computer programs. It may be a standalone application or it may be built into an integrated development environment (IDE) or web browser. Source-code ed ...
, but the content aspects reflect the programmer's talent and skills. Various
visual programming language In computing, a visual programming language (visual programming system, VPL, or, VPS) is any programming language that lets users create computer program, programs by manipulating program elements ''graphically'' rather than by specifying them '' ...
s have also been developed with the intent to resolve readability concerns by adopting non-traditional approaches to code structure and display.
Integrated development environment An integrated development environment (IDE) is a Application software, software application that provides comprehensive facilities to computer programmers for software development. An IDE normally consists of at least a source code editor, build ...
s (IDEs) aim to integrate all such help. Techniques like
Code refactoring In computer programming and software design, code refactoring is the process of restructuring existing computer code—changing the ''decomposition (computer science), factoring''—without changing its external behavior. Refactoring is intended ...
can enhance readability.


Algorithmic complexity

The academic field and the engineering practice of computer programming are both largely concerned with discovering and implementing the most efficient algorithms for a given class of problems. For this purpose, algorithms are classified into ''orders'' using so-called
Big O notation Big ''O'' notation is a mathematical notation that describes the asymptotic analysis, limiting behavior of a function (mathematics), function when the Argument of a function, argument tends towards a particular value or infinity. Big O is a memb ...
, which expresses resource use, such as execution time or memory consumption, in terms of the size of an input. Expert programmers are familiar with a variety of well-established algorithms and their respective complexities and use this knowledge to choose algorithms that are best suited to the circumstances.


Methodologies

The first step in most formal software development processes is
requirements analysis In systems engineering and software engineering, requirements analysis focuses on the tasks that determine the needs or conditions to meet the new or altered product or project, taking account of the possibly conflicting requirements of the v ...
, followed by testing to determine value modeling, implementation, and failure elimination (debugging). There exist a lot of different approaches for each of those tasks. One approach popular for requirements analysis is
Use Case In software engineering, software and systems engineering, the phrase use case is a Polysemy, polyseme with two Word sense, senses: # A usage scenario for a piece of software; often used in the plural to suggest situations where a piece of soft ...
analysis. Many programmers use forms of
Agile software development In software development, agile (sometimes written Agile) practices include requirements discovery and solutions improvement through the collaborative effort of Self-organizing communities, self-organizing and cross-functional team, cross-functi ...
where the various stages of formal software development are more integrated together into short cycles that take a few weeks rather than years. There are many approaches to the Software development process. Popular modeling techniques include Object-Oriented Analysis and Design ( OOAD) and Model-Driven Architecture ( MDA). The Unified Modeling Language ( UML) is a notation used for both the OOAD and MDA. A similar technique used for database design is Entity-Relationship Modeling ( ER Modeling). Implementation techniques include imperative languages (
object-oriented Object-oriented programming (OOP) is a programming paradigm based on the concept of "Object (computer science), objects", which can contain data and Computer program, code. The data is in the form of Field (computer science), fields (often kno ...
or procedural),
functional languages In computer science Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to Applied sc ...
, and logic languages.


Measuring language usage

It is very difficult to determine what are the most popular modern programming languages. Methods of measuring programming language popularity include: counting the number of job advertisements that mention the language, the number of books sold and courses teaching the language (this overestimates the importance of newer languages), and estimates of the number of existing lines of code written in the language (this underestimates the number of users of business languages such as COBOL). Some languages are very popular for particular kinds of applications, while some languages are regularly used to write many different kinds of applications. For example,
COBOL COBOL (; an acronym An acronym is a word or name formed from the initial components of a longer name or phrase. Acronyms are usually formed from the initial letters of words, as in ''NATO'' (''North Atlantic Treaty Organization''), but so ...
is still strong in corporate data centers often on large
mainframe computer A mainframe computer, informally called a mainframe or big iron, is a computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital ele ...
s, Fortran in engineering applications,
scripting language A scripting language or script language is a programming language that is used to manipulate, customize, and automate the facilities of an existing system. Scripting languages are usually Interpreter (computing), interpreted at Runtime (program li ...
s in
Web Web most often refers to: * Spider web A spider web, spiderweb, spider's web, or cobweb (from the archaic word ''Wikt:coppe, coppe'', meaning "spider") is a structure created by a spider out of proteinaceous spider silk extruded from its ...
development, and C in
embedded software Embedded software is computer software, written to control machines or devices that are not typically thought of as computers, commonly known as embedded systems. It is typically specialized for the particular hardware that it runs on and has ti ...
. Many applications use a mix of several languages in their construction and use. New languages are generally designed around the syntax of a prior language with new functionality added, (for example
C++ C++ (pronounced "C plus plus") is a high-level general-purpose programming language In computer software, a general-purpose programming language (GPL) is a programming language for building software in a wide variety of application Domain (so ...
adds object-orientation to C, and
Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's List ...
adds memory management and
bytecode Bytecode (also called portable code or p-code) is a form of instruction set designed for efficient execution by a software Interpreter (computing), interpreter. Unlike Human-readable code, human-readable source code, bytecodes are compact nume ...
to C++, but as a result, loses efficiency and the ability for low-level manipulation).


Debugging

Debugging is a very important task in the software development process since having defects in a program can have significant consequences for its users. Some languages are more prone to some kinds of faults because their specification does not require compilers to perform as much checking as other languages. Use of a
static code analysis In computer science, static program analysis (or static analysis) is the analysis of computer programs performed without executing them, in contrast with dynamic program analysis, which is performed on programs during their execution. The ter ...
tool can help detect some possible problems. Normally the first step in debugging is to attempt to reproduce the problem. This can be a non-trivial task, for example as with parallel processes or some unusual software bugs. Also, specific user environment and usage history can make it difficult to reproduce the problem. After the bug is reproduced, the input of the program may need to be simplified to make it easier to debug. For example, when a bug in a compiler can make it crash when
parsing Parsing, syntax analysis, or syntactic analysis is the process of analyzing a String (computer science), string of Symbol (formal), symbols, either in natural language, computer languages or data structures, conforming to the rules of a formal gra ...
some large source file, a simplification of the test case that results in only few lines from the original source file can be sufficient to reproduce the same crash. Trial-and-error/divide-and-conquer is needed: the programmer will try to remove some parts of the original test case and check if the problem still exists. When debugging the problem in a GUI, the programmer can try to skip some user interaction from the original problem description and check if remaining actions are sufficient for bugs to appear. Scripting and
breakpoint In software development Software development is the process of conceiving, specifying, designing, Computer programming, programming, software documentation, documenting, software testing, testing, and Software bugs, bug fixing involved in cre ...
ing is also part of this process. Debugging is often done with IDEs. Standalone debuggers like GDB are also used, and these often provide less of a visual environment, usually using a
command line A command-line interpreter or command-line processor uses a command-line interface (CLI) to receive command (computing), commands from a user in the form of lines of text. This provides a means of setting parameters for the environment, invokin ...
. Some text editors such as
Emacs Emacs , originally named EMACS (an acronym for "Editor MACroS"), is a family of text editors that are characterized by their extensibility. The manual for the most widely used variant, GNU Emacs, describes it as "the extensible, customizable, se ...
allow GDB to be invoked through them, to provide a visual environment.


Programming languages

Different programming languages support different styles of programming (called ''
programming paradigm Programming paradigms are a way to classify programming languages based on their features. Languages can be classified into multiple paradigms. Some paradigms are concerned mainly with implications for the execution model of the language, suc ...
s''). The choice of language used is subject to many considerations, such as company policy, suitability to task, availability of third-party packages, or individual preference. Ideally, the programming language best suited for the task at hand will be selected. Trade-offs from this ideal involve finding enough programmers who know the language to build a team, the availability of compilers for that language, and the efficiency with which programs written in a given language execute. Languages form an approximate spectrum from "low-level" to "high-level"; "low-level" languages are typically more machine-oriented and faster to execute, whereas "high-level" languages are more abstract and easier to use but execute less quickly. It is usually easier to code in "high-level" languages than in "low-level" ones. Programming languages are essential for software development. They are the building blocks for all software, from the simplest applications to the most sophisticated ones. Allen Downey, in his book ''How To Think Like A Computer Scientist'', writes: :The details look different in different languages, but a few basic instructions appear in just about every language: :*Input: Gather data from the keyboard, a file, or some other device. :*Output: Display data on the screen or send data to a file or other device. :*Arithmetic: Perform basic arithmetical operations like addition and multiplication. :*Conditional Execution: Check for certain conditions and execute the appropriate sequence of statements. :*Repetition: Perform some action repeatedly, usually with some variation. Many computer languages provide a mechanism to call functions provided by
shared libraries In computer science Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to Applied ...
. Provided the functions in a library follow the appropriate run-time conventions (e.g., method of passing
arguments An argument is a statement or group of statements called premises intended to determine the degree of truth or acceptability of another statement called conclusion. Arguments can be studied from three main perspectives: the logical, the dialectic ...
), then these functions may be written in any other language.


Programmers

Computer programmers are those who write computer software. Their jobs usually involve: *Prototyping *Coding *Debugging *
Documentation Documentation is any communicable material that is used to describe, explain or instruct regarding some attributes of an object, system or procedure, such as its parts, assembly, installation, maintenance and use. As a form of knowledge manageme ...
*
Integration Integration may refer to: Biology * Multisensory integration * Path integration * Pre-integration complex The pre-integration complex (PIC) is a nucleoprotein complex of viral genetic material and associated viral and host proteins which is capa ...
*
Maintenance Maintenance may refer to: Biological science * Maintenance of an organism * Maintenance respiration Maintenance respiration (or maintenance energy) refers to metabolism Metabolism (, from el, μεταβολή ''metabolē'', "change ...
*Requirements analysis *
Software architecture Software architecture is the fundamental structure of a software system and the discipline of creating such structures and systems. Each structure comprises software elements, relations among them, and properties of both elements and relations. ...
*Software testing *
Specification A specification often refers to a set of documented requirements to be satisfied by a material, design, product, or service. A specification is often a type of technical standard. There are different types of technical or engineering specificati ...
Although programming has been presented in the media as a somewhat mathematical subject, some research shows that good programmers have strong skills in natural human languages, and that learning to code is similar to learning a
foreign language A foreign language is a language Language is a structured system of communication. The structure of a language is its grammar and the free components are its vocabulary. Languages are the primary means by which humans communicate, and may b ...
.


See also

* ACCU *
Association for Computing Machinery The Association for Computing Machinery (ACM) is a US-based international learned society for computing. It was founded in 1947 and is the world's largest scientific and educational computing society. The ACM is a nonprofit organization, non-pr ...
*
Computer network A computer network is a set of computers sharing resources located on or provided by Node (networking), network nodes. The computers use common communication protocols over digital signal, digital interconnections to communicate with each ot ...
ing *
Hello world program ''Hello'' is a salutation A salutation is a greeting used in a Letter (message), letter or other communication. Salutations can be formal or informal. The most common form of salutation in an English letter is wed by the recipient's given n ...
* Institution of Analysts and Programmers * National Coding Week * Object hierarchy * Programming best practices *
System programming Systems programming, or system programming, is the activity of programming computer A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital elect ...
* Computer programming in the punched card era *''
The Art of Computer Programming ''The Art of Computer Programming'' (''TAOCP'') is a comprehensive monograph written by the computer scientist Donald Knuth presenting Computer programming, programming algorithms and analysis of algorithms, their analysis. Volumes 1–5 are int ...
'' *
Women in computing Women in computing were among the first programmers in the early 20th century, and contributed substantially to the industry. As technology and practices altered, the role of women as programmers has changed, and the recorded history of the fiel ...
* Timeline of women in computing


References


Sources

* * * *


Further reading

* A.K. Hartmann,
Practical Guide to Computer Simulations
', Singapore:
World Scientific World Scientific Publishing is an academic publisher of scientific, technical, and medical books and academic journal, journals headquartered in Singapore. The company was founded in 1981. It publishes about 600 books annually, along with 135 jour ...
(2009) * A. Hunt, D. Thomas, and W. Cunningham, ''The Pragmatic Programmer. From Journeyman to Master'', Amsterdam: Addison-Wesley Longman (1999) * Brian W. Kernighan, ''The Practice of Programming'', Pearson (1999) * Weinberg, Gerald M., ''The Psychology of Computer Programming'', New York: Van Nostrand Reinhold (1971) * Edsger W. Dijkstra, ''A Discipline of Programming'', Prentice-Hall (1976) * O.-J. Dahl, E.W.Dijkstra, C.A.R. Hoare, ''Structured Programming'', Academic Press (1972) * David Gries, ''The Science of Programming'', Springer-Verlag (1981)


External links

* * * {{DEFAULTSORT:Computer Programming Programming