C Langauge

 

C Langauge:

C, computer programming language developed in the early 1970s by American computer scientist Dennis M. Ritchie at Bell Laboratories (formerly AT&T Bell Laboratories). C was designed as a minimalist language to be used in writing operating systems for minicomputers, such as the DEC PDP 7, which had very limited memories compared with the mainframe computers of the period. The language was devised during 1969–73, alongside the early development of the UNIX operating system. It was based on CPL (Combined Programming Language), which had been first condensed into the B programming language—a stripped-down computer programming language—created in 1969–70 by Ken Thompson, an American computer scientist and a colleague of Ritchie. Ritchie subsequently rewrote and restored features from CPL to create C, eventually rewriting the UNIX operating system in the new language.

As the UNIX system was enhanced, a series of changes took place in C between 1977 and 1979. During this time a description of the language became widely available through a book, The C Programming Language (1978), by Brian W. Kernighan and Ritchie. In the mid-1980s it became important to establish an official standard for C, since it was being used in projects subject to commercial and government contracts. In 1983 the American National Standards Institute (ANSI) set up a committee that further amended and standardized the language. Since then C++ has been referred to as ANSI Standard C++, and it remains popular in the world of UNIX-like operating systems. C also became one of the most common programming languages used for writing other system software and applications. Descendants of C include Concurrent C, Objective C, C*, and the widely used C++. The programming language Java was introduced in 1994 as a simplified subset of C for deployment over the Internet and for use in portable devices with limited memory or limited processing capabilities

c language founder :

Dennis M. Ritchie,  (born September 9, 1941, Bronxville, Eastchester, New York, U.S.—found dead October 2011, Berkeley Heights, New Jersey), American computer scientist and cowinner of the 1983 A.M. Turing Award, the highest honour in computer science. Ritchie and the American computer scientist Kenneth L. Thompson were cited jointly for “their development of generic operating systems theory and specifically for the implementation of the UNIX operating system,” which they developed together at Bell Laboratories.

Ritchie earned a bachelor’s degree (1963) in physics and a doctorate (1968) in mathematics from Harvard University. In 1967 he joined Bell Labs, where he first worked on the Multics operating system (OS). Multics was a time-sharing system funded by the Advanced Research Projects Agency and jointly developed by researchers at the Massachusetts Institute of Technology, Bell Labs, and General Electric Co. However, AT&T Corporation (then the parent company of Bell Labs) withdrew from the project and removed its GE computers in 1969.

Upon the removal of the GE machines, Ritchie joined Thompson in developing a more flexible operating system for Bell Lab’s obsolete Digital Equipment Corporation (DEC) PDP-7 minicomputer. Within a few months they had created UNIX, a new OS not completely tied to any particular computer hardware, as earlier systems had been.

In conjunction with the development of UNIX, Ritchie contributed somewhat to Thompson’s creation of the B programming language in 1970. As they moved their operating system to a newer PDP-11 minicomputer in 1971, the shortcomings of B became apparent, and Ritchie extended the language over the next year to create the C programming language. C and its family of languages, including C++ and Java, remain among the most widely used computer programming languages. In 1973 Ritchie and Thompson rewrote UNIX in C.

Ritchie was named a fellow by Bell Labs in 1983 and was elected to the U.S. National Academy of Engineering in 1988. In 1990 he was appointed head of the System Software Research Department at Bell Labs, where he led the development of the Plan 9 (1995) and Inferno (1996) operating systems. In 1998 Ritchie and Thompson were awarded the U.S. National Medal of Technology for their development of UNIX.

History of 'c':

The C programming language was devised in the early 1970s by Dennis M. Ritchie an employee from Bell Labs (AT&T).

In the 1960s Ritchie worked, with several other employees of Bell Labs (AT&T), on a project called Multics. The goal of the project was to develop an operating system for a large computer that could be used by a thousand users. In 1969 AT&T (Bell Labs) withdrew from the project, because the project could not produce an economically useful system. So the employees of Bell Labs (AT&T) had to search for another project to work on (mainly Dennis M. Ritchie and Ken Thompson).

Ken Thompson began to work on the development of a new file system. He wrote, a version of the new file system for the DEC PDP-7, in assembler. (The new file system was also used for the game Space Travel). Soon they began to make improvements and add expansions. (They used there knowledge from the Multics project to add improvements). After a while a complete system was born. Brian W. Kernighan called the system UNIX, a sarcastic reference to Multics. The whole system was still written in assembly code.

Besides assembler and Fortran, UNIX also had an interpreter for the programming language B. ( The B language is derived directly from Martin Richards BCPL). The language B was developed in 1969-70 by Ken Thompson. In the early days computer code was written in assembly code. To perform a specific task, you had to write many pages of code. A high-level language like B made it possible to write the same task in just a few lines of code. The language B was used for further development of the UNIX system. Because of the high-level of the B language, code could be produced much faster, then in assembly.

A drawback of the B language was that it did not know data-types. (Everything was expressed in machine words). Another functionality that the B language did not provide was the use of “structures”. The lag of these things formed the reason for Dennis M. Ritchie to develop the programming language C. So in 1971-73 Dennis M. Ritchie turned the B language into the C language, keeping most of the language B syntax while adding data-types and many other changes. The C language had a powerful mix of high-level functionality and the detailed features required to program an operating system. Therefore many of the UNIX components were eventually rewritten in C (the Unix kernel itself was rewritten in 1973 on a DEC PDP-11).

The programming language C was written down, by Kernighan and Ritchie, in a now classic book called “The C Programming Language, 1st edition”. (Kernighan has said that he had no part in the design of the C language: “It’s entirely Dennis Ritchie’s work”. But he is the author of the famous “Hello, World” program and many other UNIX programs).

For years the book “The C Programming Language, 1st edition” was the standard on the language C. In 1983 a committee was formed by the American National Standards Institute (ANSI)

to develop a modern definition for the programming language C (ANSI X3J11). In 1988 they delivered the final standard definition ANSI C. (The standard was based on the book from K&R 1st ed.).

The standard ANSI C made little changes on the original design of the C language. (They had to make sure that old programs still worked with the new standard). Later on, the ANSI C standard was adopted by the International Standards Organization (ISO). The correct term should there fore be ISO C, but everybody still calls it ANSI C