Lesson-1

Introduction To C:

• The C is a general-purpose, procedural, imperative computer programming language developed in 1972 by Dennis M. Ritchie at the Bell Telephone Laboratories to develop the UNIX operating system.
•  The Unix operating system and virtually all Unix applications are written in the C language. C has now become a widely used professional language for various reasons.
  
  
  1. Easy to learn
  2. Structured language
  3. It produces efficient programs.
  4. It can handle low-level activities.
  5. It can be compiled on a variety of computers.
   

Facts about C

• C was invented to write an operating system called UNIX.
• C is a successor of B language which was introduced around 1970The language was formalized in 1988 by the American National Standard Institue (ANSI).
• By 1973 UNIX OS almost totally written in C.
• Today C is the most widely used System Programming Language.
• Most of the state of the art software have been implemented using C

Why to use C ?

• C was initially used for system development work, in particular the programs that make-up the operating system. C was adoped as a system development language because it produces code that runs nearly as fast as code written in assembly language. Some examples of the use of C might be:

1. Operating Systems
2. Language Compilers
3. Assemblers
4. Text Editors
5. Print Spoolers
6. Network Drivers
7. Modern Programs
8. Data Bases
9. Language Interpreters
10. Utilities

C Program File

• All the C programs are writen into text files with extension ".c" for example hello.c. You can use "vi" editor to write your C program into a file.

• This tutorial assumes that you know how to edit a text file and how to write programming insturctions inside a program file.

C Compilers

• When you write any program in C language then to run that program you need to compile that program using a C Compiler which converts your program into a language understandable by a computer. This is called machine language (ie. binary format). So before proceeding, make sure you have C Compiler available at your computer. It comes alongwith all flavors of Unix and Linux.

• If you are working over Unix or Linux then you can type gcc -v or cc -v and check the result. You can ask your system administrator or you can take help from anyone to identify an available C Compiler at your computer.

• If you don't have C compiler installed at your computer then you can use below given link to download a GNU C Compiler and use it.

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