INTRODUCTION WITH C LANGUAGE

      INTRODUCTION WITH C LANGUAGE

C is a powerful, efficient, general purpose structured programming language. It is a reliable, simple and easy to use therefore it has become a very popular programming language. It is not only limited to programming professionals and experts but any computer beginner who has knowledge of its syntax and programming methodology can make programs in it.

Prior to C, the available programming languages such as BASIC, COBOL and FORTRAN were not designed around structured principles. Instead they relied upon the GOTO as the primary means of program control. This was not of major concern when programs were small and simple. But i i case of large programs, a mass of tangled jumps and conditional branches made the program virtually impos sible to understand. Later a programming language, PASCAL was designed on structured principle, but it failed to include many important features and was not good for system programming. All these led to the development of the C language.

There is a close analogy between learning General English language and learning C language. Like the method of learning General English i.e. first learn alphabets, then combine them to form words, then they are combined to form sentences and then they are combined to form paragraphs. Similarly in C, using character set, we can form variables, keywords and constants which are then combined to form statements (or instructions) and which then together form a program.

Although C is a high level language but it also supports features of a low level language, so it is sometimes called a middle level language. It is actually binding the gap between a machine language and more conventional high level languages. C also contains some additional features that allow it to be used at a lower level. It is used for system programming (e.g. for writing operating systems) as well as for application programming (e.g. Programs involving complex mathematical-equations, customers billing systems). Thus, the use of C language for system programing in addition to its support for application programming makes it a middle level language.

A large number of in-built functions are included in the Clanguage, This feature helps it to write very concise source programs. The availability of a large number of library functions (in-built functions) also enhances the programming methodology

C is also a structured language. The essential feature of structured language is that it should have the ability to divide the program into small modules where each module performs a specified task. Each module can either have a sequence structure or a selection structure or a loop structure. All these modules are based on the principle of one entry and one exit concept, which is the basic concept of modular programming. This structured approach helps to give an accurate, error-free and maintainable code. Now with the use of local variables available within the functions, we can divide the program and also able to hide the usage of variables, from the rest of program. These functions hide the information from the rest of program, thus making it a structured language.

C is also a case-sensitive language. The identifiers used in uppercase letters have different meaning as compared to the same identifiers used in lowercase letters. This is considered as a disad vantage of C language.

C is programmer oriented. It enables you to manipulate individual bits in memory, thus allow ing the user to access the hardware. It is basically designed to fulfill the needs of a programmer.

Moreover, the user can add its own library functions, thereby extending the capabilities of the language.

C compilers are com monly available for computers of all sizes. (Compilers translate the entire program into machine lan guage before executing any of the instructions). C Compilers are usu ally compact and generate object programs that are small and highly efficient when compared with pro grams compiled from other high level languages. The interpreters are less efficient, though better when developing a new program (Inter preters proceed through a program by translating and then executing single instruction at a time).

Portability is another important characteristic of C Language. By the term 'portable, we mean computer independent. Programs made in C can be made to run on different machines ranging from smallest PC's through mightiest super computers.

C language is mainly used in the development of system softwares such as operating system kernel, editors, compilers, device drivers etc. as well as in the development of application softwares.

Various versions of C compiler are available till date. These include Turbo C, Borland C, Power C. QuickC, ANSI C etc. Every version is accompanied by its own set of library functions. Each library function is generally accessed in the same manner from one version to another. The current version of C language is C99. It includes some additional data types such as bool, complex, variable-length arrays, incorporation of C++ line comment(//), extension of the character type to support non-English characters and many more. Since there is a substantial change, most compilers have not yet imple mented C99.