Portal:Computer programming
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The Computer Programming Portal
Computer programming or coding is the composition of sequences of instructions, called programs, that computers can follow to perform tasks. It involves designing and implementing algorithms, step-by-step specifications of procedures, by writing code in one or more programming languages. Programmers typically use high-level programming languages that are more easily intelligible to humans than machine code, which is directly executed by the central processing unit. Proficient programming usually requires expertise in several different subjects, including knowledge of the application ___domain, details of programming languages and generic code libraries, specialized algorithms, and formal logic.
Auxiliary tasks accompanying and related to programming include analyzing requirements, testing, debugging (investigating and fixing problems), implementation of build systems, and management of derived artifacts, such as programs' machine code. While these are sometimes considered programming, often the term software development is used for this larger overall process – with the terms programming, implementation, and coding reserved for the writing and editing of code per se. Sometimes software development is known as software engineering, especially when it employs formal methods or follows an engineering design process. (Full article...)
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tcsh and sh shell windows on a Mac OS X Leopard desktop
A Unix shell is a shell that provides a command-line user interface for a Unix-like operating system. A Unix shell provides a command language that can be used either interactively or for writing a shell script. A user typically interacts with a Unix shell via a terminal emulator; however, direct access via serial hardware connections or Secure Shell are common for server systems. Although use of a Unix shell is popular with some users, others prefer to use a windowing system such as desktop Linux distribution or macOS instead of a command-line interface.
A user may have access to multiple Unix shells with one configured to run by default when the user logs in interactively. The default selection is typically stored in a user's profile; for example, in the local passwd file or in a distributed configuration system such as NIS or LDAP. A user may use other shells nested inside the default shell.
A Unix shell may provide many features including: variable definition and substitution, command substitution, filename wildcarding, stream piping, control flow structures (condition-testing and iteration), working directory context, and here document. (Full article...) -
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Scala (/ˈskɑːlɑː/ SKAH-lah) is a strongly statically typed high-level general-purpose programming language that supports both object-oriented programming and functional programming. Designed to be concise, many of Scala's design decisions are intended to address criticisms of Java.
Scala source code can be compiled to Java bytecode and run on a Java virtual machine (JVM). Scala can also be transpiled to JavaScript to run in a browser, or compiled directly to a native executable. When running on the JVM, Scala provides language interoperability with Java so that libraries written in either language may be referenced directly in Scala or Java code. Like Java, Scala is object-oriented, and uses a syntax termed curly-brace which is similar to the language C. Since Scala 3, there is also an option to use the off-side rule (indenting) to structure blocks, and its use is advised. Martin Odersky has said that this turned out to be the most productive change introduced in Scala 3.
Unlike Java, Scala has many features of functional programming languages (like Scheme, Standard ML, and Haskell), including currying, immutability, lazy evaluation, and pattern matching. It also has an advanced type system supporting algebraic data types, covariance and contravariance, higher-order types (but not higher-rank types), anonymous types, operator overloading, optional parameters, named parameters, raw strings, and an experimental exception-only version of algebraic effects that can be seen as a more powerful version of Java's checked exceptions. (Full article...) -
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Margaret Elaine Hamilton (née Heafield; born August 17, 1936) is an American computer scientist. She directed the Software Engineering Division at the MIT Instrumentation Laboratory, where she led the development of the on-board flight software for NASA's Apollo Guidance Computer for the Apollo program. She later founded two software companies, Higher Order Software in 1976 and Hamilton Technologies in 1986, both in Cambridge, Massachusetts.
Hamilton has published more than 130 papers, proceedings, and reports, about sixty projects, and six major programs. She coined the term "software engineering", stating "I began to use the term 'software engineering' to distinguish it from hardware and other kinds of engineering, yet treat each type of engineering as part of the overall systems engineering process."
On November 22, 2016, Hamilton received the Presidential Medal of Freedom from president Barack Obama for her work leading to the development of on-board flight software for NASA's Apollo Moon missions. (Full article...) -
Image 4Jobs introducing the iPhone 4, 2010
Steven Paul Jobs (February 24, 1955 – October 5, 2011) was an American businessman, inventor, and investor best known for co-founding the technology company Apple Inc. Jobs was also the founder of NeXT and chairman and majority shareholder of Pixar. He was a pioneer of the personal computer revolution of the 1970s and 1980s, along with his early business partner and fellow Apple co-founder Steve Wozniak.
Jobs was born in San Francisco in 1955 and adopted shortly afterwards. He attended Reed College in 1972 before withdrawing that same year. In 1974, he traveled through India, seeking enlightenment before later studying Zen Buddhism. He and Wozniak co-founded Apple in 1976 to further develop and sell Wozniak's Apple I personal computer. Together, the duo gained fame and wealth a year later with production and sale of the Apple II, one of the first highly successful mass-produced microcomputers.
Jobs saw the commercial potential of the Xerox Alto in 1979, which was mouse-driven and had a graphical user interface (GUI). This led to the development of the largely unsuccessful Apple Lisa in 1983, followed by the breakthrough Macintosh in 1984, the first mass-produced computer with a GUI. The Macintosh launched the desktop publishing industry in 1985 (for example, the Aldus Pagemaker) with the addition of the Apple LaserWriter, the first laser printer to feature vector graphics and PostScript. (Full article...) -
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Yoshua Bengio OC OQ FRS FRSC (born March 5, 1964) is a Canadian computer scientist, and a pioneer of artificial neural networks and deep learning. He is a professor at the Université de Montréal and scientific director of the AI institute MILA.
Bengio received the 2018 ACM A.M. Turing Award, often referred to as the "Nobel Prize of Computing", together with Geoffrey Hinton and Yann LeCun, for their foundational work on deep learning. Bengio, Hinton, and LeCun are sometimes referred to as the "Godfathers of AI". Bengio is the most-cited computer scientist globally (by both total citations and by h-index), and the most-cited living scientist across all fields (by total citations). In 2024, TIME Magazine included Bengio in its yearly list of the world's 100 most influential people. (Full article...) -
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An illustration of the linking process. Object files and static libraries are assembled into a new library or executable
A linker or link editor is a computer program that combines intermediate software build files such as object and library files into a single executable file such as a program or library. A linker is often part of a toolchain that includes a compiler and/or assembler that generates intermediate files that the linker processes. The linker may be integrated with other toolchain tools such that the user does not interact with the linker directly.
A simpler version that writes its output directly to memory is called the loader, though loading is typically considered a separate process. (Full article...) -
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C++ is a high-level, general-purpose programming language created by Danish computer scientist Bjarne Stroustrup. First released in 1985 as an extension of the C programming language, adding object-oriented (OOP) features, it has since expanded significantly over time adding more OOP and other features; as of 1997[update]/C++98 standardization, C++ has added functional features, in addition to facilities for low-level memory manipulation for systems like microcomputers or to make operating systems like Linux or Windows, and even later came features like generic programming (through the use of templates). C++ is usually implemented as a compiled language, and many vendors provide C++ compilers, including the Free Software Foundation, LLVM, Microsoft, Intel, Embarcadero, Oracle, and IBM.
C++ was designed with systems programming and embedded, resource-constrained software and large systems in mind, with performance, efficiency, and flexibility of use as its design highlights. C++ has also been found useful in many other contexts, with key strengths being software infrastructure and resource-constrained applications, including desktop applications, video games, servers (e.g., e-commerce, web search, or databases), and performance-critical applications (e.g., telephone switches or space probes).
C++ is standardized by the International Organization for Standardization (ISO), with the latest standard version ratified and published by ISO in October 2024 as ISO/IEC 14882:2024 (informally known as C++23). The C++ programming language was initially standardized in 1998 as ISO/IEC 14882:1998, which was then amended by the C++03, C++11, C++14, C++17, and C++20 standards. The current C++23 standard supersedes these with new features and an enlarged standard library. Before the initial standardization in 1998, C++ was developed by Stroustrup at Bell Labs since 1979 as an extension of the C language; he wanted an efficient and flexible language similar to C that also provided high-level features for program organization. Since 2012, C++ has been on a three-year release schedule with C++26 as the next planned standard. (Full article...) -
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Large supercomputers such as IBM's Blue Gene/P are designed to heavily exploit parallelism.
Parallel computing is a type of computation in which many calculations or processes are carried out simultaneously. Large problems can often be divided into smaller ones, which can then be solved at the same time. There are several different forms of parallel computing: bit-level, instruction-level, data, and task parallelism. Parallelism has long been employed in high-performance computing, but has gained broader interest due to the physical constraints preventing frequency scaling. As power consumption (and consequently heat generation) by computers has become a concern in recent years, parallel computing has become the dominant paradigm in computer architecture, mainly in the form of multi-core processors.
In computer science, parallelism and concurrency are two different things: a parallel program uses multiple CPU cores, each core performing a task independently. On the other hand, concurrency enables a program to deal with multiple tasks even on a single CPU core; the core switches between tasks (i.e. threads) without necessarily completing each one. A program can have both, neither or a combination of parallelism and concurrency characteristics.
Parallel computers can be roughly classified according to the level at which the hardware supports parallelism, with multi-core and multi-processor computers having multiple processing elements within a single machine, while clusters, MPPs, and grids use multiple computers to work on the same task. Specialized parallel computer architectures are sometimes used alongside traditional processors, for accelerating specific tasks. (Full article...) -
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Carphone Warehouse is a mobile phone retailer based in London, United Kingdom. In August 2014 the company became a subsidiary of Currys plc (previously named "Dixons Carphone"), which was formed by the merger of its former parent Carphone Warehouse Group with Dixons Retail. Prior to this merger, Carphone Warehouse Group was listed on the London Stock Exchange, and was a constituent of the FTSE 250 Index. Following the closure of all stand-alone UK stores in April 2020, all remaining Carphone Warehouse UK outlets were within branches of Currys 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...) -
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Kotlin (/ˈkɒtlɪn/) is a cross-platform, statically typed, general-purpose high-level programming language with type inference. Kotlin is designed to interoperate fully with Java, and the JVM version of Kotlin's standard library depends on the Java Class Library,
but type inference allows its syntax to be more concise. Kotlin mainly targets the JVM, but also compiles to JavaScript (e.g., for frontend web applications using React) or native code via LLVM (e.g., for native iOS apps sharing business logic with Android apps). Language development costs are borne by JetBrains, while the Kotlin Foundation protects the Kotlin trademark.
On 7 May 2019, Google announced that the Kotlin programming language had become its preferred language for Android app developers. Since the release of Android Studio 3.0 in October 2017, Kotlin has been included as an alternative to the standard Java compiler. The Android Kotlin compiler emits Java 8 bytecode by default (which runs in any later JVM), but allows targeting Java 9 up to 20, for optimizing, or allows for more features; has bidirectional record class interoperability support for JVM, introduced in Java 16, considered stable as of Kotlin 1.5.
Kotlin has support for the web with Kotlin/JS, through an intermediate representation-based backend which has been declared stable since version 1.8, released December 2022. Kotlin/Native (for e.g. Apple silicon support) has been declared stable since version 1.9.20, released November 2023. (Full article...) -
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Augusta Ada King, Countess of Lovelace (née Byron; 10 December 1815 – 27 November 1852), also known as Ada Lovelace, was an English mathematician and writer chiefly known for her work on Charles Babbage's proposed mechanical general-purpose computer, the Analytical Engine. She was the first to recognise that the machine had applications beyond pure calculation.
Lovelace was the only legitimate child of poet Lord Byron and reformer Anne Isabella Milbanke. All her half-siblings, Lord Byron's other children, were born out of wedlock to other women. Lord Byron separated from his wife a month after Ada was born and left England forever. He died in Greece whilst fighting in the Greek War of Independence, when she was eight. Lady Byron was anxious about her daughter's upbringing and promoted Lovelace's interest in mathematics and logic in an effort to prevent her from developing her father's perceived insanity. Despite this, Lovelace remained interested in her father, naming one son Byron and the other, for her father's middle name, Gordon. Upon her death, she was buried next to her father at her request. Although often ill in her childhood, Lovelace pursued her studies assiduously. She married William King in 1835. King was made Earl of Lovelace in 1838, Ada thereby becoming Countess of Lovelace.
Lovelace's educational and social exploits brought her into contact with scientists such as Andrew Crosse, Charles Babbage, Sir David Brewster, Charles Wheatstone and Michael Faraday, and the author Charles Dickens, contacts which she used to further her education. Lovelace described her approach as "poetical science" and herself as an "Analyst (& Metaphysician)". (Full article...) -
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JavaScript (JS) is a programming language and core technology of the web platform, alongside HTML and CSS. Ninety-nine percent of websites on the World Wide Web use JavaScript on the client side for webpage behavior.
Web browsers have a dedicated JavaScript engine that executes the client code. These engines are also utilized in some servers and a variety of apps. The most popular runtime system for non-browser usage is Node.js.
JavaScript is a high-level, often just-in-time–compiled language that conforms to the ECMAScript standard. It has dynamic typing, prototype-based object-orientation, and first-class functions. It is multi-paradigm, supporting event-driven, functional, and imperative programming styles. It has application programming interfaces (APIs) for working with text, dates, regular expressions, standard data structures, and the Document Object Model (DOM). (Full article...) -
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Linus Benedict Torvalds (born 28 December 1969) is a Finnish software engineer who is the creator and lead developer of the Linux kernel. He also created the distributed version control system Git.
He was honored, along with Shinya Yamanaka, with the 2012 Millennium Technology Prize by the Technology Academy Finland "in recognition of his creation of a new open source operating system for computers leading to the widely used Linux kernel". He is also the recipient of the 2014 IEEE Computer Society Computer Pioneer Award and the 2018 IEEE Masaru Ibuka Consumer Electronics Award. (Full article...) -
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Flowchart of using successive subtractions to find the greatest common divisor of number r and s
In mathematics and computer science, an algorithm (/ˈælɡərɪðəm/ ⓘ) is a finite sequence of mathematically rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing calculations and data processing. More advanced algorithms can use conditionals to divert the code execution through various routes (referred to as automated decision-making) and deduce valid inferences (referred to as automated reasoning).
In contrast, a heuristic is an approach to solving problems without well-defined correct or optimal results. For example, although social media recommender systems are commonly called "algorithms", they actually rely on heuristics as there is no truly "correct" recommendation.
As an effective method, an algorithm can be expressed within a finite amount of space and time and in a well-defined formal language for calculating a function. Starting from an initial state and initial input (perhaps empty), the instructions describe a computation that, when executed, proceeds through a finite number of well-defined successive states, eventually producing "output" and terminating at a final ending state. The transition from one state to the next is not necessarily deterministic; some algorithms, known as randomized algorithms, incorporate random input. (Full article...) -
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William Henry Gates III CFR (born October 28, 1955) is an American businessman and philanthropist. A pioneer of the microcomputer revolution of the 1970s and 1980s, he co-founded the software company Microsoft in 1975 with his childhood friend Paul Allen. Following the company's 1986 initial public offering (IPO), Gates became a billionaire in 1987—then the youngest ever, at age 31. Forbes magazine ranked him as the world's wealthiest person for 18 out of 24 years between 1995 and 2017, including 13 years consecutively from 1995 to 2007. He became the first centibillionaire in 1999, when his net worth briefly surpassed $100 billion. According to Forbes, as of May 2025, his net worth stood at US$115.1 billion, making him the thirteenth-richest individual in the world.
Born and raised in Seattle, Washington, Gates was privately educated at Lakeside School, where he befriended Allen and developed his computing interests. In 1973, he enrolled at Harvard University, where he took classes including Math 55 and graduate level computer science courses, but he dropped out in 1975 to co-found and lead Microsoft. He served as its CEO for the next 25 years and also became president and chairman of the board when the company incorporated in 1981. Succeeded as CEO by Steve Ballmer in 2000, he transitioned to chief software architect, a position he held until 2008. He stepped down as chairman of the board in 2014 and became technology adviser to CEO Satya Nadella and other Microsoft leaders, a position he still holds. He resigned from the board in 2020.
Over time, Gates reduced his role at Microsoft to focus on his philanthropic work with the Bill & Melinda Gates Foundation, the world's largest private charitable organization, which he and his then-wife Melinda French Gates co-chaired from 2000 until 2024. Focusing on areas including health, education, and poverty alleviation, Gates became known for his efforts to eradicate transmissible diseases such as tuberculosis, malaria, and polio. After French Gates resigned as co-chair following the couple's divorce, the foundation was renamed the Gates Foundation, with Gates as its sole chair. (Full article...)
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Image 1Stephen Wolfram is a British-American computer scientist, physicist, and businessman. He is known for his work in computer science, mathematics, and in theoretical physics.
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Image 2GNOME Shell, GNOME Clocks, Evince, gThumb and GNOME Files at version 3.30, in a dark theme
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Image 6An IBM Port-A-Punch punched card
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Image 7Partial view of the Mandelbrot set. Step 1 of a zoom sequence: Gap between the "head" and the "body" also called the "seahorse valley".
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Image 8Partial map of the Internet based on the January 15, 2005 data found on opte.org. Each line is drawn between two nodes, representing two IP addresses. The length of the lines are indicative of the delay between those two nodes. This graph represents less than 30% of the Class C networks reachable by the data collection program in early 2005.
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Image 9Ada Lovelace was an English mathematician and writer, chiefly known for her work on Charles Babbage's proposed mechanical general-purpose computer, the Analytical Engine. She was the first to recognize that the machine had applications beyond pure calculation, and to have published the first algorithm intended to be carried out by such a machine. As a result, she is often regarded as the first computer programmer.
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Image 10Grace Hopper at the UNIVAC keyboard, c. 1960. Grace Brewster Murray: American mathematician and rear admiral in the U.S. Navy who was a pioneer in developing computer technology, helping to devise UNIVAC I. the first commercial electronic computer, and naval applications for COBOL (common-business-oriented language).
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Image 11This image (when viewed in full size, 1000 pixels wide) contains 1 million pixels, each of a different color.
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Image 12Deep Blue was a chess-playing expert system run on a unique purpose-built IBM supercomputer. It was the first computer to win a game, and the first to win a match, against a reigning world champion under regular time controls. Photo taken at the Computer History Museum.
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Image 14A view of the GNU nano Text editor version 6.0
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Image 15A lone house. An image made using Blender 3D.
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Image 16A head crash on a modern hard disk drive
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Image 17Margaret Hamilton standing next to the navigation software that she and her MIT team produced for the Apollo Project.
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Image 18Output from a (linearised) shallow water equation model of water in a bathtub. The water experiences 5 splashes which generate surface gravity waves that propagate away from the splash locations and reflect off of the bathtub walls.
Did you know? - load more entries

- ... that the study of selection algorithms has been traced to an 1883 work of Lewis Carroll on how to award second place in single-elimination tournaments?
- ... that a "hacker" with blog posts written by ChatGPT was at the center of an online scavenger hunt promoting Avenged Sevenfold's album Life Is but a Dream...?
- ... that both Thackeray and Longfellow bought paintings by Fanny Steers?
- ... that a pink skin for Mercy in the video game Overwatch helped raise more than $12 million for breast cancer research?
- ... that Cornell University's student-oriented programming language dialect was made available to other universities but required a "research grant" payment in exchange?
- ... that NATO was once targeted by a group of "gay furry hackers"?
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