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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Image 1
The source code for a computer program in C. The gray lines are comments that explain the program to humans. When compiled and run, it will give the output "Hello, world!".
A programming language is a system of notation for writing computer programs.
Programming languages are described in terms of their syntax (form) and semantics (meaning), usually defined by a formal language. Languages usually provide features such as a type system, variables, and mechanisms for error handling. An implementation of a programming language is required in order to execute programs, namely an interpreter or a compiler. An interpreter directly executes the source code, while a compiler produces an executable program.
Computer architecture has strongly influenced the design of programming languages, with the most common type (imperative languages—which implement operations in a specified order) developed to perform well on the popular von Neumann architecture. While early programming languages were closely tied to the hardware, over time they have developed more abstraction to hide implementation details for greater simplicity.
Thousands of programming languages—often classified as imperative, functional, logic, or object-oriented—have been developed for a wide variety of uses. Many aspects of programming language design involve tradeoffs—for example, exception handling simplifies error handling, but at a performance cost. Programming language theory is the subfield of computer science that studies the design, implementation, analysis, characterization, and classification of programming languages. (Full article...) -
Image 2In computing, a compiler is a computer program that translates computer code written in one programming language (the source language) into another language (the target language). The name "compiler" is primarily used for programs that translate source code from a high-level programming language to a low-level programming language (e.g. assembly language, object code, or machine code) to create an executable program.
There are many different types of compilers which produce output in different useful forms. A cross-compiler produces code for a different CPU or operating system than the one on which the cross-compiler itself runs. A bootstrap compiler is often a temporary compiler, used for compiling a more permanent or better optimised compiler for a language.
Related software include decompilers, programs that translate from low-level languages to higher level ones; programs that translate between high-level languages, usually called source-to-source compilers or transpilers; language rewriters, usually programs that translate the form of expressions without a change of language; and compiler-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...) -
Image 3Laboratory Virtual Instrument Engineering Workbench (LabVIEW) is a graphical system design and development platform produced and distributed by National Instruments, based on a programming environment that uses a visual programming language. It is widely used for data acquisition, instrument control, and industrial automation. It provides tools for designing and deploying complex test and measurement systems.
The visual (aka graphical) programming language is called "G" (not to be confused with G-code). It is a dataflow language originally developed by National Instruments. LabVIEW is supported on a variety of operating systems (OSs), including macOS and other versions of Unix and Linux, as well as Microsoft Windows.
The latest versions of LabVIEW are LabVIEW 2024 Q3 (released in July 2024) and LabVIEW NXG 5.1 (released in January 2021). National Instruments released the free for non-commercial use LabVIEW and LabVIEW NXG Community editions on April 28, 2020. (Full article...) -
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W3sDesign Interpreter Design Pattern UML
In computer science, an interpreter is a computer program that directly executes instructions written in a programming or scripting language, without requiring them previously to have been compiled into a machine language program. An interpreter generally uses one of the following strategies for program execution:- Parse the source code and perform its behavior directly;
- Translate source code into some efficient intermediate representation or object code and immediately execute that;
- Explicitly execute stored precompiled bytecode made by a compiler and matched with the interpreter's virtual machine.
Early versions of Lisp programming language and minicomputer and microcomputer BASIC dialects would be examples of the first type. Perl, Raku, Python, MATLAB, and Ruby are examples of the second, while UCSD Pascal is an example of the third type. Source programs are compiled ahead of time and stored as machine independent code, which is then linked at run-time and executed by an interpreter and/or compiler (for JIT systems). Some systems, such as Smalltalk and contemporary versions of BASIC and Java, may also combine two and three types. Interpreters of various types have also been constructed for many languages traditionally associated with compilation, such as Algol, Fortran, Cobol, C and C++. (Full article...) -
Image 5Information technology (IT) is a set of related fields within information and communications technology (ICT), that encompass computer systems, software, programming languages, data and information processing, and storage. Information technology is an application of computer science and computer engineering.
The term is commonly used as a synonym for computers and computer networks, but it also encompasses other information distribution technologies such as television and telephones. Several products or services within an economy are associated with information technology, including computer hardware, software, electronics, semiconductors, internet, telecom equipment, and e-commerce.
An information technology system (IT system) is generally an information system, a communications system, or, more specifically speaking, a computer system — including all hardware, software, and peripheral equipment — operated by a limited group of IT users, and an IT project usually refers to the commissioning and implementation of an IT system. IT systems play a vital role in facilitating efficient data management, enhancing communication networks, and supporting organizational processes across various industries. Successful IT projects require meticulous planning and ongoing maintenance to ensure optimal functionality and alignment with organizational objectives. (Full article...) -
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The IBM Blue Gene/P supercomputer installation in 2007 at the Argonne Leadership Computing Facility located in the Argonne National Laboratory, in Lemont, Illinois, US
Fortran (/ˈfɔːrtræn/; formerly FORTRAN) is a third-generation, compiled, imperative programming language that is especially suited to numeric computation and scientific computing.
Fortran was originally developed by IBM with a reference manual being released in 1956; however, the first compilers only began to produce accurate code two years later. Fortran computer programs have been written to support scientific and engineering applications, such as numerical weather prediction, finite element analysis, computational fluid dynamics, plasma physics, geophysics, computational physics, crystallography and computational chemistry. It is a popular language for high-performance computing and is used for programs that benchmark and rank the world's fastest supercomputers.
Fortran has evolved through numerous versions and dialects. In 1966, the American National Standards Institute (ANSI) developed a standard for Fortran to limit proliferation of compilers using slightly different syntax. Successive versions have added support for a character data type (Fortran 77), structured programming, array programming, modular programming, generic programming (Fortran 90), parallel computing (Fortran 95), object-oriented programming (Fortran 2003), and concurrent programming (Fortran 2008). (Full article...) -
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Linus Benedict Torvalds (/ˈliːnəs ˈtɔːrvɔːldz/ ⓘ LEE-nəs TOR-vawldz, Finland Swedish: [ˈliːnʉs ˈtuːrvɑlds] ⓘ; 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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The Greek lowercase omega (ω) character is used to represent Null in database theory.
In SQL, null or NULL is a special marker used to indicate that a data value does not exist in the database. Introduced by the creator of the relational database model, E. F. Codd, SQL null serves to fulfill the requirement that all true relational database management systems (RDBMS) support a representation of "missing information and inapplicable information". Codd also introduced the use of the lowercase Greek omega (ω) symbol to represent null in database theory. In SQL,NULL
is a reserved word used to identify this marker.
A null should not be confused with a value of 0. 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" (we know that he owns none) or "null" (we do not know how many he owns). In a database table, the column 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 is quite different from most programming languages, where a null value of a reference means it is not pointing to any object. (Full article...) -
Image 9Ronald Paul "Ron" Fedkiw (born February 27, 1968) is a full professor in the Stanford University department of computer science and a leading researcher in the field of computer graphics, focusing on topics relating to physically based simulation of natural phenomena and machine learning. His techniques have been employed in many motion pictures. He has earned recognition at the 80th Academy Awards and the 87th Academy Awards as well as from the National 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 the Star Wars, Harry Potter, Terminator, and Pirates of the Caribbean franchises. Fedkiw has designed a platform that has been used to create many of the movie world's most advanced special effects since it was first used on the T-X character in Terminator 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 the visual 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...) -
Image 10Forth is a stack-oriented programming language and interactive integrated development environment designed by Charles H. "Chuck" Moore and first used by other programmers in 1970. Although not an acronym, the language's name in its early years was often spelled in all capital letters as FORTH. The FORTH-79 and FORTH-83 implementations, which were not written by Moore, became de facto standards, and an official technical standard of the language was published in 1994 as ANS Forth. A wide range of Forth derivatives existed before and after ANS Forth. The free and open-source software Gforth implementation is actively maintained, as are several commercially supported systems.
Forth typically combines a compiler with an integrated command shell, where the user interacts via subroutines called words. Words can be defined, tested, redefined, and debugged without recompiling or restarting the whole program. All syntactic elements, including variables, operators, and control flow, are defined as words. A stack is used to pass parameters between words, leading to a Reverse Polish notation style.
For much of Forth's existence, the standard technique was to compile to threaded code, which can be interpreted faster than bytecode. One of the early benefits of Forth was size: an entire development environment—including compiler, editor, and user programs—could fit in memory on an 8-bit or similarly limited system. No longer constrained by space, there are modern implementations that generate optimized machine code like other language compilers. The relative simplicity of creating a basic Forth system has led to many personal and proprietary variants, such as the custom Forth used to implement the bestselling 1986 video game Starflight from Electronic Arts. (Full article...) -
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Python is a high-level, general-purpose programming language. Its design philosophy emphasizes code readability with the use of significant indentation.
Python is dynamically type-checked and garbage-collected. It supports multiple programming paradigms, including structured (particularly procedural), object-oriented and functional programming. It is often described as a "batteries included" language due to its comprehensive standard library.
Guido van Rossum began working on Python in the late 1980s as a successor to the ABC programming language, and he first released it in 1991 as Python 0.9.0. Python 2.0 was released in 2000. Python 3.0, released in 2008, was a major revision not completely backward-compatible with earlier versions. Python 2.7.18, released in 2020, was the last release of Python 2. (Full article...) -
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Charles Babbage KH FRS (/ˈbæbɪdʒ/; 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 by some to be "father of the computer". He is credited with inventing the first mechanical computer, the difference engine, that eventually led to more complex electronic designs, though all the essential ideas of modern computers are to be found in his analytical engine, programmed using a principle openly borrowed from the Jacquard loom. As part of his computer work, he also designed the first computer printers. He had a broad range of interests in addition to his work on computers covered in his 1832 book Economy of Manufactures and Machinery. He was an important figure in the social scene in London, and is credited with importing the "scientific soirée" from France with his well-attended Saturday evening soirées. His varied work in other fields has led him to be described as "pre-eminent" among the many polymaths of his century.
Babbage, who died before the complete successful engineering of many of his designs, including his Difference Engine and Analytical Engine, remained a prominent figure in the ideating of computing. Parts of his incomplete mechanisms are on display in the Science Museum in London. In 1991, a functioning difference engine was constructed from the original plans. Built to tolerances achievable in the 19th century, the success of the finished engine indicated that Babbage's machine would have worked. (Full article...) -
Image 13Structured Query Language (SQL) (pronounced /ˌɛsˌkjuˈɛl/ S-Q-L; or alternatively as /ˈsiːkwəl/ "sequel")
is a domain-specific language used to manage data, especially in a relational database management system (RDBMS). It is particularly useful in handling structured data, i.e., data incorporating relations among entities and variables.
Introduced in the 1970s, SQL offered two main advantages over older read–write APIs such as ISAM or VSAM. Firstly, it introduced the concept of accessing many records with one single command. Secondly, it eliminates the need to specify how to reach a record, i.e., with or without an index.
Originally based upon relational algebra and tuple relational calculus, SQL consists of many types of statements, which may be informally classed as sublanguages, commonly: Data query Language (DQL), Data Definition Language (DDL), Data Control Language (DCL), and Data Manipulation Language (DML). (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...) -
Image 15In computer systems a loader is the part of an operating system that is responsible for loading programs and libraries. It is one of the essential stages in the process of starting a program, as it places programs into memory and prepares them for execution. Loading a program involves either memory-mapping or copying the contents of the executable file containing the program instructions into memory, and then carrying out other required preparatory tasks to prepare the executable for running. Once loading is complete, the operating system starts the program by passing control to the loaded program code.
All operating systems that support program loading have loaders, apart from highly specialized computer systems that only have a fixed set of specialized programs. Embedded systems typically do not have loaders, and instead, the code executes directly from ROM or similar. In order to load the operating system itself, as part of booting, a specialized boot loader is used. In many operating systems, the loader resides permanently in memory, though some operating systems that support virtual memory may allow the loader to be located in a region of memory that is pageable.
In the case of operating systems that support virtual memory, the loader may not actually copy the contents of executable files into memory, but rather may simply declare to the virtual memory subsystem that there is a mapping between a region of memory allocated to contain the running program's code and the contents of the associated executable file. (See memory-mapped file.) The virtual memory subsystem is then made aware that pages with that region of memory need to be filled on demand if and when program execution actually hits those areas of unfilled memory. This may mean parts of a program's code are not actually copied into memory until they are actually used, and unused code may never be loaded into memory at all. (Full article...)
Selected images
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Image 1A view of the GNU nano Text editor version 6.0
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Image 2Grace 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 3Ada 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 4This image (when viewed in full size, 1000 pixels wide) contains 1 million pixels, each of a different color.
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Image 5An IBM Port-A-Punch punched card
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Image 6A head crash on a modern hard disk drive
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Image 7GNOME Shell, GNOME Clocks, Evince, gThumb and GNOME Files at version 3.30, in a dark theme
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Image 8Margaret Hamilton standing next to the navigation software that she and her MIT team produced for the Apollo Project.
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Image 11Partial 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 13Deep 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 14Output 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.
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Image 15A lone house. An image made using Blender 3D.
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Image 17Partial 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 18Stephen Wolfram is a British-American computer scientist, physicist, and businessman. He is known for his work in computer science, mathematics, and in theoretical physics.
Did you know? - load more entries

- ... 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 both Thackeray and Longfellow bought paintings by Fanny Steers?
- ... that the programming language Acorn System BASIC was so non-standard that one commenter suggested that using it on the BBC Micro would be a disaster?
- ... that the Gale–Shapley algorithm was used to assign medical students to residencies long before its publication by Gale and Shapley?
- ... 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?
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