what is a data structure
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INTRODUCTION TODATA STRUCTURE
CHAPTER
1
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ROAD MAP Data representation
Abstract data type
Need of data structure
Data type
Difference between ADT, DT andDS
Classification of data structure
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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
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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ROAD MAP
Data representation
Abstract data type
Need of data structure
Data type
Difference between ADT, DT andDS
Classification of data structure
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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.
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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
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Derived Data Type
These are non-primitive data typewhich are derived from primitive data
type. Examples:
array
structure
union
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ROAD MAP
Need of data structure
Data representation
Abstract data type
Data type
Difference between ADT, DT andDS
Classification of data structure
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Classification of data structureData structure
Linear Datastructure
Non-primitive
Trees
Stacks
Graph
Array Linked
ListQueue
Non-linear Datastructure
Primitive
integer float pointerchar
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