In theSQL databasequery language,null orNULL is a special marker used to indicate that a data value does not exist in thedatabase. Introduced by the creator of therelationaldatabase model,E. F. Codd, SQL null serves to fulfill the requirement that alltrue relational database management systems (RDBMS) support a representation of "missing information and inapplicable information". Codd also introduced the use of the lowercase Greekomega (ω) symbol to represent null indatabase theory. In SQL,NULL is areserved word used to identify this marker.

A null should not be confused with a value of0. A null indicates a lack of a value, which is not the same as a zero value. For example, consider the question "How many books does Adam own?" The answer may be "zero" (weknow that he ownsnone) or "null" (wedo not know how many he owns). In a database table, thecolumn reporting this answer would start with no value (marked by null), and it would not be updated with the value zero until it is ascertained that Adam owns no books.

In SQL, null is a marker, not a value. This usage differs from most programming languages, where anull value of a reference means it is not pointing to anyobject. (Full article...)

Java is ahigh-level,general-purpose,memory-safe,object-orientedprogramming language. It is intended to letprogrammerswrite once, run anywhere (WORA), meaning thatcompiled Java code can run on all platforms that support Java without the need to recompile. Java applications are typically compiled tobytecode that can run on anyJava virtual machine (JVM) regardless of the underlyingcomputer architecture. Thesyntax of Java is similar toC andC++, but has fewerlow-level facilities than either of them. The Java runtime provides dynamic capabilities (such asreflection and runtime code modification) that are typically not available in traditional compiled languages.

Java gained popularity shortly after its release, and has been a popular programming language since then. Java was the third most popular programming language in 2022^[update] according toGitHub. Although still widely popular, there has been a gradual decline in use of Java in recent years withother languages using JVM gaining popularity.

Java was designed byJames Gosling atSun Microsystems. It was released in May 1995 as a core component of Sun'sJava platform. The original andreference implementation Javacompilers, virtual machines, andclass libraries were released by Sun underproprietary licenses. As of May 2007, in compliance with the specifications of theJava Community Process, Sun hadrelicensed most of its Java technologies under theGPL-2.0-only license.Oracle, which bought Sun in 2010, offers its ownHotSpot Java Virtual Machine. However, the officialreference implementation is theOpenJDK JVM, which is open-source software used by most developers and is the default JVM for almost all Linux distributions. (Full article...)

Eiffel is anobject-orientedprogramming language designed byBertrand Meyer (an object-orientation proponent and author ofObject-Oriented Software Construction) and Eiffel Software. Meyer conceived the language in 1985 with the goal of increasing the reliability of commercial software development. The first version was released in 1986. In 2005, theInternational Organization for Standardization (ISO) released atechnical standard for Eiffel.

The design of the language is closely connected with the Eiffel programming method. Both are based on a set of principles, includingdesign by contract,command–query separation, theuniform-access principle, thesingle-choice principle, theopen–closed principle, andoption–operand separation.

Many concepts initially introduced by Eiffel were later added intoJava,C#, and other languages. New language design ideas, particularly through theEcma/ISO standardization process, continue to be incorporated into the Eiffel language. (Full article...)

Carphone Warehouse is a mobile phone retailer based in London, United Kingdom. In August 2014 the company became a subsidiary ofCurrys plc (previously named "Dixons Carphone"), which was formed by the merger of its former parent Carphone Warehouse Group withDixons Retail. Prior to this merger, Carphone Warehouse Group was listed on theLondon Stock Exchange, and was a constituent of theFTSE 250 Index. Following the closure of all stand-alone UK stores in April 2020, all remaining Carphone Warehouse UK outlets were within branches ofCurrys PC World. In April 2021, the Carphone Warehouse business in Ireland (including all stand-alone and co-located branches and the website) was closed with immediate effect. Currys continued to use the Carphone Warehouse brand in the United Kingdom, online and, until 2021, inside Currys stores. (Full article...)

Incomputing, acompiler issoftware thattranslates computer code written in oneprogramming language (thesource language) into another language (thetarget language). The name "compiler" is primarily used for programs that translatesource code from ahigh-level programming language to alow-level programming language (e.g.assembly language,object code, ormachine code) to create anexecutable program.

There are many different types of compilers which produce output in different useful forms. Across-compiler produces code for a differentCPU oroperating system than the one on which the cross-compiler itself runs. Abootstrap compiler is often a temporary compiler, used for compiling a more permanent or better optimized compiler for a language.

Related software includedecompilers, programs that translate from low-level languages to higher level ones; programs that translate between high-level languages, usually calledsource-to-source compilers ortranspilers; languagerewriters, usually programs that translate the form ofexpressions without a change of language; andcompiler-compilers, compilers that produce compilers (or parts of them), often in a generic and reusable way so as to be able to produce many differing compilers. (Full article...)

PHP is ageneral-purposescripting language geared towardsweb development. It was originally created byDanish-CanadianprogrammerRasmus Lerdorf in 1993 and released in 1995. The PHPreference implementation is now produced by the PHP Group. PHP was originally an abbreviation ofPersonal Home Page, but it now stands for therecursivebackronymPHP: Hypertext Preprocessor.

PHP code is usually processed on aweb server by a PHPinterpreter implemented as amodule, adaemon or aCommon Gateway Interface (CGI) executable. On aweb server, the result of theinterpreted and executed PHP code—which may be any type of data, such as generatedHTML orbinary image data—would form the whole or part of anHTTP response. Variousweb template systems, webcontent management systems, andweb frameworks exist that can be employed to orchestrate or facilitate the generation of that response. Additionally, PHP can be used for programming tasks outside the web context, though most non-web uses are rare. PHP code can also be directly executed from thecommand line.

The standard PHP interpreter, powered by theZend Engine, isfree software released under thePHP License. PHP has been widely ported and can be deployed on most web servers on a variety ofoperating systems andplatforms. (Full article...)

Aprogramming language is an artificial language for expressingcomputer programs.

Programming languages typically allow software to bewritten in ahuman readable manner.

Execution of a program requires animplementation. There are two main approaches for implementing a programming language –compilation, where programs are compiled ahead-of-time tomachine code, andinterpretation, where programs are directly executed. In addition to these two extremes, some implementations use hybrid approaches such asjust-in-time compilation andbytecode interpreters. (Full article...)

BASIC (Beginner's All-purpose Symbolic Instruction Code) is a family ofgeneral-purpose,high-level programming languages designed for ease of use.The original version was created byJohn G. Kemeny andThomas E. Kurtz atDartmouth College in 1964. They wanted to enable students in non-scientific fields to use computers. At the time, nearly all computers required writing custom software, which onlyscientists andmathematicians tended to learn.

In addition to the programming language, Kemeny and Kurtz developed theDartmouth Time-Sharing System (DTSS), which allowed multiple users to edit and run BASIC programs simultaneously on remote terminals. This general model became popular onminicomputer systems like thePDP-11 andData General Nova in the late 1960s and early 1970s.Hewlett-Packard produced an entire computer line for this method of operation, introducing theHP2000 series in the late 1960s and continuing sales into the 1980s. Many early video games trace their history to one of these versions of BASIC.

The emergence ofmicrocomputers in the mid-1970s led to the development of multiple BASIC dialects, includingMicrosoft BASIC in 1975. Due to the tinymain memory available on these machines, often 4 KB, a variety ofTiny BASIC dialects were also created. BASIC was available for almost any system of the era and became thede facto programming language forhome computer systems that emerged in the late 1970s. ThesePCs almost always had aBASIC interpreter installed by default, often in the machine'sfirmware or sometimes on aROM cartridge. (Full article...)

Computer hardware includes the physical parts of acomputer, such as thecentral processing unit (CPU),random-access memory (RAM),motherboard,computer data storage,graphics card,sound card, andcomputer case. It includes external devices such as amonitor,mouse,keyboard, andspeakers.

By contrast,software is a set of written instructions that can be stored and run by hardware. Hardware derived its name from the fact it ishard or rigid with respect to changes, whereas software issoft because it is easy to change.

Hardware is typically directed by the software to execute any command orinstruction. A combination of hardware and software forms a usablecomputing system, althoughother systems exist with only hardware. (Full article...)

C# (/ˌsiːˈʃɑːrp/seeSHARP) is ageneral-purposehigh-levelprogramming language supporting multipleparadigms. C# encompassesstatic typing,strong typing,lexically scoped,imperative,declarative,functional,generic,object-oriented (class-based), andcomponent-oriented programming disciplines.

The principal designers of the C# programming language wereAnders Hejlsberg, Scott Wiltamuth, and Peter Golde fromMicrosoft. It was first widely distributed in July 2000 and was later approved as aninternational standard byEcma (ECMA-334) in 2002 andISO/IEC (ISO/IEC 23270 and 20619) in 2003. Microsoft introduced C# along with.NET Framework and MicrosoftVisual Studio, both of which are technically speaking,closed-source. At the time, Microsoft had no open-source products. Four years later, in 2004, afree and open-source project calledMono began, providing across-platformcompiler andruntime environment for the C# programming language. A decade later, Microsoft releasedVisual Studio Code (code editor),Roslyn (compiler), andthe unified .NET platform (software framework), all of which support C# and are free, open-source, and cross-platform. Mono also joined Microsoft but was not merged into .NET.
As of November 2025,^[update] the most recent stable version of the language is C# 14. (Full article...)

SNOBOL (StriNg Oriented and symBOlic Language) is a series ofprogramming languages developed between 1962 and 1967 atAT&TBell Laboratories byDavid J. Farber,Ralph Griswold and Ivan P. Polonsky, culminating in SNOBOL4. It was one of a number oftext-string-oriented languages developed during the 1950s and 1960s; others includedCOMIT andTRAC. Despite the similar name, it is entirely unlikeCOBOL.

SNOBOL4 stands apart from most programming languages of its era by having patterns as afirst-class data type, a data type whose values can be manipulated in all ways permitted to any other data type in the programming language, and by providing operators for patternconcatenation andalternation. SNOBOL4 patterns are a type of object and admit various manipulations, much like laterobject-oriented languages such asJavaScript whose patterns are known asregular expressions. In addition SNOBOL4 strings generated during execution can be treated as programs and either interpreted or compiled and executed (as in theeval function of other languages).

SNOBOL4 was quite widely taught in larger U.S. universities in the late 1960s and early 1970s and was widely used in the 1970s and 1980s as a text manipulation language in thehumanities. (Full article...)

Ronald Paul "Ron" Fedkiw (born February 27, 1968) is afull professor in theStanford University department ofcomputer science and a leading researcher in the field ofcomputer graphics, focusing on topics relating to physically based simulation of natural phenomena and machine learning. His techniques have been employed in manymotion pictures. He has earned recognition at the80th Academy Awards and the87th Academy Awards as well as from theNational Academy of Sciences.

His first Academy Award was awarded for developing techniques that enabled many technically sophisticated adaptations including the visual effects in 21st century movies in theStar Wars,Harry Potter,Terminator, andPirates of the Caribbeanfranchises. Fedkiw has designed aplatform that has been used to create many of the movie world's most advanced special effects since it was first used on theT-X character inTerminator 3: Rise of the Machines. His second Academy Award was awarded for computer graphics techniques for special effects for large scale destruction. Although he has won an Oscar for his work, he does not design thevisual effects that use his technique. Instead, he has developed a system that other award-winning technicians and engineers have used to create visual effects for some of the world's most expensive and highest-grossing movies. (Full article...)

Microsoft is a multinational computer technology corporation. Microsoft was founded on April 4, 1975, byBill Gates andPaul Allen inAlbuquerque, New Mexico. Its current best-selling products are theMicrosoft Windowsoperating system;Microsoft Office, a suite of productivity software;Xbox, a line of entertainment of games, music, and video;Bing, a line of search engines; andMicrosoft Azure, a cloud services platform.

In 1980, Microsoft formed a partnership withIBM to bundle Microsoft's operating system with IBM computers; with that deal, IBM paid Microsoft a royalty for every sale. In 1985, IBM requested Microsoft to develop a new operating system for their computers calledOS/2. Microsoft produced that operating system, but also continued to sell their own alternative, which proved to be in direct competition with OS/2. Microsoft Windows eventually overshadowed OS/2 in terms of sales. When Microsoft launched several versions of Microsoft Windows in the 1990s, they had captured over 90% market share of the world's personal computers.

As of June 30, 2015, Microsoft has a global annual revenue of US$86.83 billion (~$112 billion in 2024) and 128,076 employees worldwide. It develops, manufactures, licenses, and supports a wide range ofsoftware products for computing devices. (Full article...)

InC++computer programming,allocators are a component of theC++ Standard Library. The standardlibrary provides severaldata structures, such aslist andset, commonly referred to ascontainers. A common trait among these containers is their ability to change size during theexecution of theprogram. To achieve this, some form ofdynamic memory allocation is usually required. Allocators handle all the requests forallocation and deallocation of memory for a given container. The C++ Standard Library provides general-purpose allocators that are used by default; however, custom allocators may also be supplied by theprogrammer.

Allocators were invented byAlexander Stepanov as part of theStandard Template Library (STL). They were originally intended as a means to make the library more flexible and independent of the underlyingmemory model, allowing programmers to utilize custompointer andreference types with the library. However, in the process of adopting STL into theC++ standard, the C++ standardization committee realized that a completeabstraction of the memory model would incur unacceptableperformance penalties. To remedy this, the requirements of allocators were made more restrictive. As a result, the level of customization provided by allocators is more limited than was originally envisioned by Stepanov.

Nevertheless, there are many scenarios where customized allocators are desirable. Some of the most common reasons for writing custom allocators include improving performance of allocations by usingmemory pools, and encapsulating access to different types of memory, likeshared memory orgarbage-collected memory. In particular, programs with many frequent allocations of small amounts of memory may benefit greatly from specialized allocators, both in terms of running time andmemory footprint. (Full article...)

Haskell (/ˈhæskəl/) is ageneral-purpose,statically typed,purely functionalprogramming language withtype inference andlazy evaluation. Haskell pioneered several programming languagefeatures includingtype classes fortype-safeoperator overloading andmonadicinput/output (IO). It is named afterlogicianHaskell Curry. Haskell's main implementation is theGlasgow Haskell Compiler (GHC).

Haskell'ssemantics are historically based on those of theMiranda programming language, which served to focus the efforts of the initial Haskell working group. The last formal specification of the language was made in July 2010, while the development of GHC continues to expand Haskell via language extensions.

Haskell is used in academia and industry. As of May 2021^[update], Haskell was the 28th most popular programming language byGoogle searches for tutorials, and made up less than 1% of active users on theGitHub source code repository. (Full article...)