The Origin and History of C

C was developed by Dennis Ritchie in the early 1970's (Deitel, page 7).

It was influenced by earlier languages B and CPL (a job control language).
C is one of the earliest of the currently used imperative higher-order languages, and as such is closer in several ways to assembler than later languages like Pascal, Modula, or Ada.
As with UNIX, it is written primarily in lower-level C, with only a small kernel in assembler (implementing, for example, the basic integer and floating-point operations).

The Kernighan and Ritchie book (The C Programming Language) was for years a de facto standard for C.

It was only weakly type-checked, and arbitrary type-casts and pointer arithmetic were features of the coding style of early C.
The positive features of C included
1. preprocessing (using macro expansions based on hardware configuration, presence of other files, etc.)
2. initialization at declaration time
3. a powerful include facility allowing multifile specification and a tool make (developed by Stu Feldman at Bell Labs) to allow graceful compilation/recompilation of these linked files
4. extensive libraries for inclusion
5. and (for the time) general and structured control statements.
Other notable features of C are block-local variables and flat scope; all procedures are functions and all parameters are passed by value, leading to an additional role for pointers.

Many constructs passed by the C compiler often lead to trouble, and tools such as LINT were developed as preprocessor adjuncts to catch some of these.
Many implementations also added constructs such as the void type and enumerations to promote expressivity and type-checking.

These changes and others were included in C in 1988 by the ANSI C standard. The ANSI C standard borrows many features of C++, and adds others. The main change was a change in the method of specification of functions for type-checking and self-documentation.

Until recently, C was principally an imperative UNIX language. More recently, two other trends have emerged: one, the extension of C to object-oriented and parallel versions such as C++; the other, the development of PC versions and development environments, including Borland's Turbo C and C++.