What is a Data Structure

7/30/2019 What is a Data Structure

1/31

INTRODUCTION TODATA STRUCTURE

CHAPTER

1


2/31

ROAD MAP Data representation

Abstract data type

Need of data structure

Data type

Difference between ADT, DT andDS

Classification of data structure


3/31

Data Data is collection of numbers, alphabets

& symbols combined to represent

information.Atomic data: it is non-decomposable

entity. Example: integer or char

Composite data: it is a composition ofatomic data.

Example: date

day

month

year


4/31

DATA REPRESENTATIONData is represented using differentmethods like hierarchical method.

The basic unit is bit.

Eight bits together form one byte whichrepresents a character.

one or more than one characters areused to form a string.


5/31

let us discuss how the primitive or basic datatypes of any language are internally

represented in memory.

Integer Representation The positive data is represented using

binary number system.8 4 2 1

2^3 2^2 2^1 2^0

For negative binary numbers themethods of representation used areones complement and twoscomplement.


6/31

Real Number Representation The method used to represent real numbers in

computers is floating-point notation. Realnumber is represented by a mantissa andexponent.

For example, if the base is fixed as 10, 209.52 could be represented as 20952 x 10-2. The mantissa is 20952 and exponent is 2.

Both the mantissa and exponents are twoscomplement binary integers. For example,20952 can be represented as 1 0 1 0 0 0 111 0 11 in binary form.


7/31

Character Representation

It is used to store character as well asnumeric information i.e. alpha-numeric data.

1 1 0 0 0 0 0 0 -> A and 1 1 0 0 0 0 0 1 -> B.

Then, finally AB -> 11 0 0 0 0 0 0 11 0 0 0 0 0 1.


8/31


9/31

Abstract Data Types

Abstract Data Type (ADT): a definitionfor a data type solely in terms of a set

of values and a set of operations onthat data type.

Each ADT operation is defined by its

inputs and outputs.

Encapsulation: Hide implementationdetails.


10/31

ADT An ADT is defined as a

mathematical model of the data

objects that make up a data typeas well as the functions thatoperate on these objects.

ADT acts as a useful guideline toimplement a data type correctly.


11/31


12/31

EXAMPLES: INTEGER ADT1>INTEGER-ADT -

set of numbers (-1, -2, 3....-} &set of whole numbers {O. 1,2.. +}.

2>INTEGER-ADT operations i.eaddition

subtraction

multiplication, etc.


13/31


14/31


15/31


16/31

NEED OF A DATA STRUCTURE

Data structure is needed:

Give knowledge about how to organize

data. How to control flow of data.

How to design structure of data.

How to implement structure to reducecomplexity & increases efficiency ofalgorithm.


17/31

Organizing Data

Any organization for a collection of records

can be searched, processed in any order,or modified.

The choice of data structure and algorithm

can make the difference between aprogram running in a few seconds or manydays.


18/31

ROAD MAP

Data representation

Abstract data type


Data type




19/31


20/31

NEED OF DATA TYPE

Think of a universal data type - has twodisadvantages:

Large volume of memory will be occupiedby even a small size of data. Different interpretations for different types

of data would become very difficult.

Data type - optimum use of memory

- defined way to interpretthe bit strings.


21/31

PRIMITIVE DATA TYPE

Primitive data types are basic data typeof any language that forms the basic

unit for the data structure defined bythe user.

A primitive type defines how the data

will be internally represented in, stored,and retrieved from the memory


22/31


23/31

Derived Data Type

These are non-primitive data typewhich are derived from primitive data

type. Examples:

array

structure

union


24/31


25/31


26/31


27/31

ROAD MAP


Data representation

Abstract data type

Data type




28/31

Classification of data structureData structure

Linear Datastructure

Non-primitive

Trees

Stacks

Graph

Array Linked

ListQueue

Non-linear Datastructure

Primitive

integer float pointerchar


29/31


30/31


31/31

What is a Data Structure

Documents