Learn C language

 

Programming Language

   Programming language is an artificial language. Designed to express computations that can be performed by a machine,   particularly a computer. Programming languages can be used to create programs that  Control the behavior of a machine, To express algorithms precisely, or as a mode of human communication.

C- LANGUAGE

 C language is a general-purpose computer programming language. Developed in 1972 by Dennis Ritchie at the Bell Telephone Laboratories. It is used to implement both System Software and Application Software.

1.The UNIX OS was totally written in C by 1973.

2.Today C is the most widely used and popular System Programming Language.

3.Most of the state-of-the-art software have been implemented using C.

4.Today's most popular Linux OS and RBDMS MySQL have been written in C.

Different Programming Paradigms

Procedural – implement algorithms via functions (variables, functions, etc.)

Modular – partition program into modules (separate compilation)

Object-Oriented – divide problem into classes (data hiding, inheritance)

Abstract – separate interface from implementation (abstract classes).

Generic – manipulate arbitrary data types (STL:  containers, algorithms).

Scripting-scripting languages are usually interpreted at runtime rather than compiled.

Why C-Language

• C is a structured/Procedural programming language
• It is case sensitive language.
• It supports functions that enables easy maintainability of code, by breaking large file into smaller modules
• Comments in C provides easy readability
• C is a powerful language.
• And its compiler is available for almost all Operating System

Applications of C Language

• Adobe Systems 
• Google
• Mozilla
• Image Systems
• MySQL
• Alias System – Autodesk Maya
• Winamp Media Player                                                                                                                  

Elements of C-Program

• Syntax (Rules),Structure
• Comments
• Key words, Reserve words
• Variables
• Data type
• Operators
• Statements

Program Structure

A sample C Program:

---include section & Header Files

#include<stdio.h> 

void main()

{

--other statements

}

For Example:

Consider the following single-level function:

main()

{

 /*print a message*/

 printf("Welcome to C");

    }

In the preceding function:

main(): Is the first function to be executed.

(): Are used for passing parameters to a function.

Header Files

• The files that are specified in the include section is called as header file
• These are precompiled files that has some functions defined in them
• We can call those functions in our program by supplying parameters
• Header file is given an extension .h
• C Source file is given an extension .c

We can include header files in two ways:

    #include<stdio.h>

    #include "stdio.h”

The <stdio.h> is located a particular Directory which is having in Header Directory  or include directory. 

But when we write "stdio.h" processor start searching for this header file from current directory and then in parent directories. 

Main function

• This is the entry point of a program
• When a file is executed, the start point is the main function
• From main function the flow goes as per the programmers choice.
• There may or may not be other functions written by user in a program
• Main function is compulsory for any c program

Running a C-Program

• Type a program, it is known as Source Code.
• Save it with .c extension.
• Compile the program ( Alt+F9) – This will generate an Object code(.obj file)
• Run the program (Ctrl+F9)
• In different compiler we have different option for compiling and running. 

Comments in C

Single line comment
    // (double slash)
    Termination of comment is by pressing enter key
Multi line comment
    /*…. 
    …….*/
This can span over to multiple lines