01. INTRODUCTION TO C

C is a general-purpose, structured programming language. Its instructions consist of terms that resemble algebraic expressions, augmented by certain English keyword such as if, else,for,do and while. In this respect C resembles other high-level structured programming languages such as Pascal and FORTRAN. C also contains certain additional features, however, that allow it to be used at a lower level, thus bridging the gap between machine language and the more conventional high-label languages. This flexibility allows C to be use for systems programming as well as for applications programming.

  C is characterized by the ability to write very concise source programs, due in part to the large number of operators included within the language. It has a relatively small instruction set, though actual implementations include extensive library functions which enhance the basic instructions. Furthermore, the language encourages users to write additional library functions of their own. Thuse the features and capabilities of the language can easily be extended by the user.

  C compilers are commonly available for computers of all size, and C interpreters are becoming increasingly common. The compilers are usually compact, and they generate object programs that are small interpreters are less efficient, though they are easier to use when developing a new program. Many programmers begin with an interpreter, and then switch to a compiler once the program has been debugged.

  Another important characteristic of  C is that its programs are highly portable, even more so than with other high-level languages. The reason for this is that C relegates most computer-dependent features to its library functions. Thus, every version of C is accompanied by its own set of library functions, which are written for the particular characteristics of the host computer . These library functions are relatively standardized, however, and each individual library function is generally accessed in the same manner from one version of C to another. Therefore,most C programs can be processed on many different computers with little or on alteration.