By Suresh Rawat
- History of C Programming Language
C is a programming language developed at AT & T's Bell Laboratories of USA in1972. It was designed and written by a man named Denis Ritchie. In the late seventies C began to replace the more familiar language of that time like PL/I, ALGOL, etc.
C is a general purpose language which has been closely associated with the UNIX operating system for which it was developed since the system and most of the programs that run it are written in C.
ANSI C stands emerged in the early 1980s, this book was split into two titles: The original was still called programming in C, and the title that converted ANSI C was called programming in ANSI C. This was done because it took several years for the compiler vendors to release their ANSI C compiler and for them to become ubiquitous. It was initially designed for programming UNIX operating system. Now the software tool as well as the C compiler as written in C. Major parts of popular operating system like Windows, UNIX, LINUX it still written in C. This is because even today when it comes to performance (speed of execution) nothing beats C. Moreover, if one is to extend the operating system to work with new device one needs to write device driver programs, These programs are exclusively written in C. C seems so popular is because it is reliable, simple and easy to use. Often heard today is C has been already superseded by language like C++,C#, and Java.
- Basic Structure of C Program
1). Documentation section: The documentation section consist of a set of comment lines giving the name of the
program, the author and other details, which the programmer would like to user later.
2). Link section: The link section provides instructions to the compiler to the link functions from the system library
such as using the #include directive.
3). Definition
section: The
definition section defines all symbolic constants such using the #define
directive.
Global declaration section: There are some variables that are used in more than one function. Such variables are called global variables and are declared in the global declaration section that is outside of all the functions. This section also declares all the user-defined functions.
a). main () function section: Every C program must have one main function section . This section contains two parts;
declaration part and executable part
i. Declaration part: The declaration part declares all the variables used in the executable part.
ii. Executable part: There is at least one statement in the executable part. These two part must appear between the opening and closing braces. The program execution beings at the opening brace and ends at the closing brace. The closing brace of main function is the logical end of the program. All statements in the declaration and executable part end with a semicolon.
b). Subprogram section: If the program is multi- function
program then the subprogram section contains all the user-
defined function that are called in the main () function. User-defined functions are generally placed immediately
after the main () function, although they may appear in any order.
Thanks sir
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