Tagged unionIn computer science, a tagged union, also called a variant, variant record, choice type, discriminated union, disjoint union, sum type or coproduct, is a data structure used to hold a value that could take on several different, but fixed, types. Only one of the types can be in use at any one time, and a tag field explicitly indicates which one is in use. It can be thought of as a type that has several "cases", each of which should be handled correctly when that type is manipulated.
Procedural programmingProcedural programming is a programming paradigm, derived from imperative programming, based on the concept of the procedure call. Procedures (a type of routine or subroutine) simply contain a series of computational steps to be carried out. Any given procedure might be called at any point during a program's execution, including by other procedures or itself. The first major procedural programming languages appeared circa 1957–1964, including Fortran, ALGOL, COBOL, PL/I and BASIC. Pascal and C were published circa 1970–1972.
Array slicingIn computer programming, array slicing is an operation that extracts a subset of elements from an array and packages them as another array, possibly in a different dimension from the original. Common examples of array slicing are extracting a substring from a string of characters, the "ell" in "hello", extracting a row or column from a two-dimensional array, or extracting a vector from a matrix. Depending on the programming language, an array slice can be made out of non-consecutive elements.
Directive (programming)In computer programming, a directive or pragma (from "pragmatic") is a language construct that specifies how a compiler (or other translator) should process its input. Directives are not part of the grammar of a programming language, and may vary from compiler to compiler. They can be processed by a preprocessor to specify compiler behavior, or function as a form of in-band parameterization. In some cases directives specify global behavior, while in other cases they only affect a local section, such as a block of programming code.
B (programming language)B is a programming language developed at Bell Labs circa 1969 by Ken Thompson and Dennis Ritchie. B was derived from BCPL, and its name may possibly be a contraction of BCPL. Thompson's coworker Dennis Ritchie speculated that the name might be based on Bon, an earlier, but unrelated, programming language that Thompson designed for use on Multics. B was designed for recursive, non-numeric, machine-independent applications, such as system and language software.
Void typeThe void type, in several programming languages derived from C and Algol68, is the return type of a function that returns normally, but does not provide a result value to its caller. Usually such functions are called for their side effects, such as performing some task or writing to their output parameters. The usage of the void type in such context is comparable to procedures in Pascal and syntactic constructs which define subroutines in Visual Basic. It is also similar to the unit type used in functional programming languages and type theory.
Stropping (syntax)In computer language design, stropping is a method of explicitly marking letter sequences as having a special property, such as being a keyword, or a certain type of variable or storage location, and thus inhabiting a different namespace from ordinary names ("identifiers"), in order to avoid clashes. Stropping is not used in most modern languages – instead, keywords are reserved words and cannot be used as identifiers.
Euler (programming language)Euler is a programming language created by Niklaus Wirth and Helmut Weber, conceived as an extension and generalization of ALGOL 60. The designers' goals were to create a language that is: Simpler, yet more flexible, than ALGOL 60 Useful and processed with reasonable efficiency Definable with rigorous formality Available sources indicate that Euler was operational by 1965. Euler employs a general data type concept. In Euler, arrays, procedures, and switches are not quantities which are declared and named by identifiers: in contrast to ALGOL, they are not quantities on the same level as variables.
C shellThe C shell (csh or the improved version, tcsh) is a Unix shell created by Bill Joy while he was a graduate student at University of California, Berkeley in the late 1970s. It has been widely distributed, beginning with the 2BSD release of the Berkeley Software Distribution (BSD) which Joy first distributed in 1978. Other early contributors to the ideas or the code were Michael Ubell, Eric Allman, Mike O'Brien and Jim Kulp. The C shell is a command processor which is typically run in a text window, allowing the user to type and execute commands.
Bounds checkingIn computer programming, bounds checking is any method of detecting whether a variable is within some bounds before it is used. It is usually used to ensure that a number fits into a given type (range checking), or that a variable being used as an array index is within the bounds of the array (index checking). A failed bounds check usually results in the generation of some sort of exception signal. As performing bounds checking during each use can be time-consuming, it is not always done.
