C Language Main Topics

8/2/2019 C Language Main Topics

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C LANGUAGEMAIN TOPICS

Presented By

P Sreenivasulu Reddy


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INDEX

Introduction

First Program

Constants , Variables & Data types

Loops

Control Structure

Functions

Pointers

Arrays

Strings Structures & Unions

File Handling Concepts

Graphics.


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INTRODUCTION

C was developed by Dennis Ritchie at Bell Laboratories in 1972. Most of its principles and ideas were taken from the earlier language B, BCPL

and CPL.

CPL was developed jointly between the Mathematical Laboratory at the

University of Cambridge and the University of London Computer Unit in 1960s.

CPL (Combined Programming Language) was developed with the purpose of

creating a language that was capable of both machine independent programmingand would allow the programmer to control the behavior of individual bits of

information. But the CPL was too large for use in many applications.

In 1967, BCPL (Basic Combined Programming Language) was created as a scaled

down version of CPL while still retaining its basic features. This process was

continued by Ken Thompson. He made B Language during working at Bell Labs.

B Language was a scaled down version of BCPL. B Language was written for thesystems programming. In 1972, a co-worker of Ken Thompson, Dennis Ritchie

developed C Language by taking some of the generality found in BCPL to the B

language.


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First Project done used by C-Language :

The original PDP-11 version of the Unix system was developed in assembly

language. In 1973, C language had become powerful enough that most of the Unix

kernel was rewritten in C. This was one of the first operating system kernels

implemented in a language other than assembly.


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FIRSTPROGRAM

C Language is a case sensitive language.

Program Structure:This section consist of set

of comment lines.

This section consist

of set of Header

files and Constant

values

The variables are declared

before the main ( ) function as

well as user defined functions

are called global variables.

The variable declaration is a part of C

program and all the variables are used

in main ( ) function should be declared

in the local declaration section is called

local variables.

These statements are building

blocks of a program. They represent

instructions to the computer to

perform a specific task (operations).

These are subprograms, generally, a

subprogram is a function and these

functions are written by the user are

called user ; defined functions.


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CONSTANTS, VARIABLES & DATA TYPES

C constants : The alphabets, numbers and special symbols when properly

combined form constants, variables and keywords. A constant is an entity that does notchange.

Ex: Pie=3.14;

o Variables : A variable is an entity that may change it value. In any program wetypically do lots of calculations.

Types of Variables

There are two main types of variables in C: numeric variables that hold onlynumbers or values, and string variables that hold text, from one to severalcharacters long.

Ex: var a=Shubh soft Solutions ;

var b=5;

Keywords :A keyword is a word that is part of C Language itself. Thesewords have predefined meanings and these words cannot be used as variable

names.

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C Language Main Topics