C is a general-purpose high level language that was originally developed by Dennis Ritchie for the Unix operating system. It was first implemented on the Digital Eqquipment Corporation PDP-11 computer in 1972.

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.

• Easy to learn

• Structured language

• It produces efficient programs.

• It can handle low-level activities.

• 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 1970

• The 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:

• Operating Systems
• Language Compilers
• Assemblers
• Text Editors
• Print Spoolers
• Network Drivers
• Modern Programs
• Data Bases
• Language Interpreters
• 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.

To know more about compilation you can go through this small tutorial Learn Makefile.