C Introduction

C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system. Although C was designed for implementing system software,it is also widely used for developing portable application software.C is one of the most widely used programming languages of all time and there are very few computer architectures for which a C compiler does not exist. C has greatly influenced many other popular programming languages, most notably C++, which began as an extension to C.

C History

Developed between 1969 and 1973 along with Unix
Due mostly to Dennis Ritchie
Designed for systems programming
1)Operating systems
2)Utility programs
3)Compilers
4)Filters

Original machine (DEC PDP-11) was very small
1)24K bytes of memory, 12K used for operating system
2)Written when computers were big, capital equipment
3)Group would get one, develop new language, OS

Characteristics of C

1)Small size 
2)Extensive use of function calls 
3)Loose typing -- unlike PASCAL 
4)Structured language 
5) Low level (BitWise) programming readily available 
6)Pointer implementation - extensive use of pointers for memory, array, structures and functions. 

C Program Structure

A C program basically has the following form: 
1)Preprocessor Commands 
2)Type definitions 
3)Function prototypes -- declare function types and variables passed to function. 
4) Variables 
5)Functions 

We must have a main() function.