C is a general-purpose programming language. It has been closely associated with the UNIX operating system where it was developed, since both the system and most of the programs that run on it are written in C. The language, however, is not tied to any one operating system or machine and although it has been called a ``system programming language because it is useful for writing compilers and operating systems, it has been used equally well to write major programs in many different domains.
The computing world has undergone a revolution since the publication of The C programming language in 1978. Big computers are much bigger, and personal computers have capabilities that rival mainframes of a decade ago. During this time, C has changed too, although only modestly, and it has spread far beyond its origins as the language of the UNIX operating system
As a programming language, C is rather like Pascal or Fortran.. Values are stored in variables.
Programs are structured by defining and calling functions. Program flow is controlled using loops, if
statements and function calls. Input and output can be directed to the terminal or to files. Related data
can be stored together in arrays or structures.
