The Development of the C Language

                                    The Development of the C Language
                                                               Dennis M. Ritchie

                                                 Bell Labs/Lucent Technologies

                                                    Murray Hill, NJ 07974 USA

                      dmr@belllabs.com

The C programming language was devised in the early 1970s as a system

implementation language for the nascent Unix operating system. Derived from

the typeless language BCPL, it evolved a type structure; created on a tiny

machine as a tool to improve a meager programming environment, it has become

one of the dominant languages of today. This paper studies its evolution.

Introduction

This paper is about the development of the C programming language, the influences on it, and the

conditions under which it was created. For the sake of brevity, I omit full descriptions of C itself,

its parent B [Johnson 73] and its grandparent BCPL [Richards 79], and instead concentrate on

characteristic elements of each language and how they evolved.

C came into being in the years 19691973,

in parallel with the early development of the

Unix operating system; the most creative period occurred during 1972. Another spate of changes

peaked between 1977 and 1979, when portability of the Unix system was being demonstrated. In

the middle of this second period, the first widely available description of the language appeared:

The C Programming Language,

in the middle 1980s, the language was officially standardized by the ANSI X3J11 committee,

which made further changes. Until the early 1980s, although compilers existed for a variety of

machine architectures and operating systems, the language was almost exclusively associated

with Unix; more recently, its use has spread much more widely, and today it is among the languages

most commonly used throughout the computer industry.

History: the setting

The late 1960s were a turbulent era for computer systems research at Bell Telephone Laboratories

[Ritchie 78] [Ritchie 84]. The company was pulling out of the Multics project [Organick

75], which had started as a joint venture of MIT, General Electric, and Bell Labs; by 1969, Bell

Labs management, and even the researchers, came to believe that the promises of Multics could

be fulfilled only too late and too expensively. Even before the GE645

Multics machine was

removed from the premises, an informal group, led primarily by Ken Thompson, had begun

investigating alternatives.

Thompson wanted to create a comfortable computing environment constructed according to

his own design, using whatever means were available. His plans, it is evident in retrospect,

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Copyright 1993 Association for Computing Machinery, Inc. This electronic reprint made available by the

author as a courtesy. For further publication rights contact ACM or the author. This article was presented at

Second History of Programming Languages conference, Cambridge, Mass., April, 1993.often called the ‘white book’ or ‘K&R’ [Kernighan 78]. Finally,