Programming language

A programming language is a formal constructed language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs to control the behavior of a machine or to express algorithms.

The earliest known programmable machine preceded the invention of the digital computer and is the automatic flute player described in the 9th century by the brothers Musa in Baghdad, at the time a major centre of knowledge. From the early 1800s, "programs" were used to direct the behavior of machines such as Jacquard looms and player pianos. Thousands of different programming languages have been created, mainly in the computer field, and many more still are being created every year. Many programming languages require computation to be specified in an imperative form (i.e., as a sequence of operations to perform), while other languages use other forms of program specification such as the declarative form (i.e. the desired result is specified, not how to achieve it).

Brian Kernighan

Brian Wilson Kernighan (/ˈkɜːrnᵻhæn/; born January 1, 1942) is a Canadian computer scientist who worked at Bell Labs alongside Unix creators Ken Thompson and Dennis Ritchie and contributed to the development of Unix. He is also coauthor of the AWK and AMPL programming languages. The "K" of K&R C and the "K" in AWK both stand for "Kernighan". Since 2000 Brian Kernighan has been a Professor at the Computer Science Department of Princeton University, where he is also the Undergraduate Department Representative.

Kernighan's name became widely known through co-authorship of the first book on the C programming language with Dennis Ritchie. Kernighan affirmed that he had no part in the design of the C language ("it's entirely Dennis Ritchie's work"). He authored many Unix programs, including ditroff.

In collaboration with Shen Lin he devised well-known heuristics for two NP-complete optimization problems: graph partitioning and the travelling salesman problem. (In a display of authorial equity, the former is usually called the Kernighan–Lin algorithm, while the latter is styled Lin–Kernighan.)

P. J. Plauger

Phillip James (Bill) Plauger (born January 13, 1944, Petersburg, West Virginia) is an author and entrepreneur and computer programmer. He has written and co-written articles and books about programming style, software tools, and the C programming language, as well as works of science fiction.

Plauger worked at Bell Labs from 1969 to 1975, where he coauthored Elements of Programming Style and Software Tools with Brian Kernighan. In 1978, he founded Whitesmiths, the first company to sell a C compiler and Unix-like operating system (Idris). He has since been involved in C and C++ standardization and is now the president of Dinkumware. In January 2009 he became the convener of the ISO C++ standards committee, but in October 2009 he tendered his resignation after failing to pass a resolution to stop processing any new features in order to facilitate the promised shipping date for the C++0x standard.

Plauger has been credited with inventing pair programming while leading Whitesmiths Ltd.

AWK

AWK is an interpreted programming language designed for text processing and typically used as a data extraction and reporting tool. It is a standard feature of most Unix-like operating systems.

The AWK language is a data-driven scripting language consisting of a set of actions to be taken against streams of textual data – either run directly on files or used as part of a pipeline – for purposes of extracting or transforming text, such as producing formatted reports. The language extensively uses the string datatype, associative arrays (that is, arrays indexed by key strings), and regular expressions. While AWK has a limited intended application domain and was especially designed to support one-liner programs, the language is Turing-complete, and even the early Bell Labs users of AWK often wrote well-structured large AWK programs.

AWK was created at Bell Labs in the 1970s, and its name is derived from the family names of its authors – Alfred Aho, Peter Weinberger, and Brian Kernighan. The acronym is pronounced the same as the name of the bird auk (which acts as an emblem of the language such as on The AWK Programming Language book cover – the book is often referred to by the abbreviation TAPL). When written in all lowercase letters, as awk, it refers to the Unix or Plan 9 program that runs scripts written in the AWK programming language.

The C Programming Language

The C Programming Language (sometimes referred to as K&R, after its authors' initials) is a well-known computer programming book written by Brian Kernighan and Dennis Ritchie, the latter of whom originally designed and implemented the language, as well as co-designed the Unix operating system with which development of the language was closely intertwined. The book was central to the development and popularization of the C programming language and is still widely read and used today. Because the book was co-authored by the original language designer, and because the first edition of the book served for many years as the de facto standard for the language, the book was regarded by many to be the authoritative reference on C.

History

The first edition of the book, published in 1978, was the first widely available book on the C programming language. C was created by Dennis Ritchie. Brian Kernighan wrote the first C tutorial. The authors came together to write the book in conjunction with the language's early development at AT&T Bell Labs. The version of C described in this book is sometimes referred to as K&R C (after the book's authors), often to distinguish this early version from the later version of C standardized as ANSI C.