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LECTURE 01
Abstract Data Types, Elementary Data Structures and
Arrays
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ABSTRACT DATA TYPES
• Abstract Data Type is an organized collection of
information and a set of operations used to manage
that information.
• e.g. Whole numbers (integers) and arithmetic operators
for addition, subtraction, multiplication and division.
• e.g. Flight reservation
Basic operations: find empty seat, reserve a seat,
cancel a seat assignment
• Data, operations, and relations are studied
independent of implementation.
•
What not how is the focus.
Superior Uni- DSA2014 BSSE
ADT AND DS
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• Abstract data type a
new type describes
properties and
operations
• Each ADT operation is
defined by its inputs
and outputs
• Collection of elements
or we can say
information.
• Logical form
• A data structure is the
physical
implementation of an
ADT.
• Each operation
associated with the ADT
is implemented by one
or more subroutines in
the implementation.
• How collection is stored
in memory
• Physical/ Concrete form
Stack is ADT with push, pop operations, but can we say about stack
data structure if I mean I used stack implemented as an array in my
algorithm? And why heap isn't ADT
Superior Uni- DSA2014 BSSE
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Data Type
ADT:
Type
Operations
Data Items:
Logical Form
Data Structure:
Storage Space
Subroutines
Data Items:
Physical Form
Superior Uni- DSA2014 BSSE
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ARRAYS
• An array is a series of elements of the same type placed
in contiguous memory locations that can be individually
referenced by adding an index to a unique identifier
• The lowest address corresponds to the first element and
the highest address to the last element.
• One dimensional array
• Two Dimensional array
Superior Uni- DSA2014 BSSE
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Declaring Arrays:
type arrayName [ arraySize ];
double balance[10];
Initializing array
double balance[5] = {1000.0, 2.0, 3.4, 17.0, 50.0};
Accessing Array Elements:
double salary = balance[9];
Superior Uni- DSA2014 BSSE
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Superior Uni- DSA2014 BSSE
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Superior Uni- DSA2014 BSSE
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Superior Uni- DSA2014 BSSE
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2D ARRAY
• Simplest form of multidimensional array
• A two-dimensional array can be think as a table,
which will have x number of rows and y number
of columns
• Most high level languages support arrays with more than one dimension.
• 2D arrays are useful when data has to be arranged in tabular form.
• Higher dimensional arrays appropriate when several characteristics
associated
with
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Uni- DSA2014
BSSEdata.
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Declaring 2D Array
type arrayName [ x ][ y ];
Initializing 2D Array:
int a[3][4] = { {0, 1, 2, 3} , {4, 5, 6, 7} , {8, 9, 10, 11} }; or
int a[3][4] = {0,1,2,3,4,5,6,7,8,9,10,11};
Accessing Two-Dimensional Array Elements:
int val = a[2][3];
Superior Uni- DSA2014 BSSE
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Superior Uni- DSA2014 BSSE