Object Oriented Programming Language (OOP)

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Object Oriented Programming Language (OOP)
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• Presented by Ustaz Mutaz Elradi Saad alla Saeed
• Faculty of Science Technologies
• Nile Valley University
• Sudan , Atbara

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Course Outline

• OOP Concept
• OOP History
• Basic Concept
• Classes Types
• Encapsulation
• Inheritance
• Private Inheritance
• Protected Inheritance
• Public Inheritance

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• Multiple Inheritance
• Polymorphism
• OOP With C Language

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Explanation

• A Class is a way to bind the data and its
  associated functions together. All the elements
  of a class are private by default, even elements
  can be declared as public or protected. An object
  is an instance of a class.
• Syntax
• class class-name
• accessspecifier
• private data and functions

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• In the above syntax the every class has a unique
  name, the "accessspecifier" can either private,
  public, protected. The "protected" is used when
  inhertinace is applied.

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Example

• include ltiostream.hgt
• class dat
• private
• int sdata
• public
• void setdat( int a)
• sdata a
• void show( )
• cout ltlt "\nSet data is " ltlt sdata

void main() dat x,y x.setdat(1000)
y.setdat(1245) x.show() y.show()
Result Set Data is1000 Set Data is1245
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• In the above class example the "private" object
  "sdata" is used only within the function. But the
  functions "setdat", "show" are used in the main
  function since they are "public".

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Access specifiers

• defines the access rights for the statements or
  functions that follows it until another access
  specifier or till the end of a class. The three
  types of access specifiers are "private",
  "public", "protected".
• private The members declared as "private" can be
  accessed only within the same class and not from
  outside the class.
• public The members declared as "public" are
  accessible within the class as well as from
  outside the class.
• protected The members declared as "protected"
  cannot be accessed from outside the class, but
  can be accessed from a derived class. This is
  used when inheritaance is applied to the members
  of a class.

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Nested class

• Nested class is a class defined inside a class,
  that can be used within the scope of the class in
  which it is defined. In C nested classes are
  not given importance because of the strong and
  flexible usage of inheritance. Its objects are
  accessed using "NestDisplay".

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Example

• include ltiostream.hgt
• class Nest
• public
• class Display
• private
• int s
• public
• void sum( int a, int b)
• s ab
• void show( )
• cout ltlt "\nSum of a and b is " ltlt s

void main() NestDisplay x
x.sum(12, 10) x.show()
Result Sum of a and b is22
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• In the above example, the nested class
  "Display" is given as "public" member of the
  class "Nest".

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Local class

• Explanation
• Local class is a class defined inside a
  function. Following are some of the rules for
  using these classes.
• Global variables declared above the function can
  be used with the scope operator "".
• Static variables declared inside the function can
  also be used.
• Automatic local variables cannot be used.
• It cannot have static data member objects.
• Member functions must be defined inside the local
  classes.
• Enclosing functions cannot access the private
  member objects of a local class.

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Example
include ltiostream.hgt int y void
g() int main() g()
return 0 void g()
class local public void
put( int n) yn

int get() return y ab
ab.put(20) cout ltlt "The value assigned
to y is"ltlt ab.get()
ResultThe value assigned to y is20
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• In the above example, the local class
  "local" uses the variable "y" which is declared
  globally. Inside the function it is used using
  the "" operator. The object "ab" is used to
  set, get the assigned values in the local class.

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• Explanation
• Object Oriented programming is method of
  programming where -
• a system is considered as a collection of
  objects that interact together to accomplish
  certain tasks. Objects are entities that
  encapsulate data and procedures that operate on
  the data.
• In OOPS first a concept known as "Object Oriented
  Analysis (OOA)" is used to specify the objects in
  term of real world requirements, their behavior
  and interactions required. The next concept would
  be the "Object Oriented Design (OOD)" that
  converts these real-time requirements as a
  hierarchy of objects in terms of software
  development requirement. Finally OOPS is used to
  implement the requirements using the C
  programming language.
• The main purpose of object oriented programming
  is to simplify the design, programming and most
  importantly debugging a program. So to modify a
  particular data, it is easy to identify which
  function to use. To add additional features it is
  easy to identify where to add functions and its
  related data.

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• Following are the basic elements of Object
  oriented programming(OOPS)
• Object
• Classes
• Inheritance
• Dynamic Binding
• Polymorphism
• Message Passing
• Encapsulation

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Objects

• Explanation
• Objects are instance of a class, that
  interact with each other at runtime. In OOPs,
  Objects are declared at the end of the class
  definition or after the "" braces. They can be
  of any type based on its declaration

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Example

• include ltiostream.hgt
• class Cube
• public
• int cub( val)
• r valvalval return r
• void show()
• cout ltlt "The cube is" ltlt r
• private
• int val, r x

void main() Cube x x.cub(2)
x.show()
ResultThe cbe is 8
In the above example "x" is an object of the
class "Cube used to access the functions inside
the class.
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Classes

• Explanation has the data and its associated
  function wrapped in it. Classes are also known as
  a collection of similar objects or objects of
  same type. In the OOPs concept the variables
  declared inside a class are known as "Data
  Members" and the functions are known as "Member
  Functions".

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Syntax

• class class-name
• private
• variable declaration
• function declaration
• public
• variable declaration
• function declaration

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Example

• include ltiostream.hgt
• class Square
• private
• int side, a
• public
• int area( side)
• a sideside
• return a
• void show()
• cout ltlt "The area is" ltlt a

void main() Square x
x.area(10) x.show()
ResultThe area is 100
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• In the above OOPs example the class "square" has
  functions "area" and "show" to calculate the area
  of the square and to display the area. so all
  these are objects that are related to the class
  "Square".

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The End of lecture
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Explanation

• Inheritance is a method by which new classes are
  created or derived from the existing classes.
  Using Inheritance some qualities of the base
  classes are added to the newly derived class,
  apart from its own features The advantage of
  using "Inheritance" is due to the reusability of
  classes in multiple derived classes. The ""
  operator is used for inheriting a class.

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The following table lists the visibility of the
base class members in the derived classes
  Derived Class Visibility Derived Class Visibility Derived Class Visibility
Base Class Visibility Public derivation Private derivation Protected derivation
Private Not inherited Not inherited Not inherited
Protected Protected Private Protected
Public Public Private Protected
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Following are the different types of inheritance
followed in C.

• Single Inheritance
• Multiple Inheritance
• Hierarchical Inheritance
• Multilevel Inheritance
• Hybrid Inheritance

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Example

• include ltiostream.hgt
• class Value
• protected
• int val
• public
• void set_values (int a)
• vala
• class Square public Value
• public
• int square()
• return (valval)

int main () Square sq sq.set_values (5)
cout ltlt "The square of 5 is" ltlt sq.square()
ltlt endl return 0
ResultThe square of 5 is 25
In the above example the object "val" of class
"Value" is inherited in the derived class
"Square".
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Explanation

• Single Inheritance is method in which a derived
  class has only one base class.

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Example

• include ltiostream.hgt
• class Value
• protected
• int val
• public
• void set_values (int a)
• vala
• class Cube public Value
• public
• int cube()
• return (valvalval)

int main () Cube cub cub.set_values (5)
cout ltlt "The Cube of 5 is" ltlt cub.cube() ltlt
endl return 0
ResultThe Cube of 5 is 125
In the above example the derived class "Cube" has
only one base class "Value". This is the single
inheritance OOP's concept.
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Multiple Inheritance

• Explanation
• Multiple Inheritance is a method by which a
  class is derived from more than one base class.

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Example

• include ltiostream.hgt
• using namespace std
• class Square
• protected
• int l
• public
• void set_values (int x)
• lx
• class CShow
• public
• void show(int i)
• void CShowshow (int i)
• cout ltlt "The area of the square
  is" ltlt i ltlt endl

int main () Area r r.set_values
(5) r.show(r.area()) return 0

ResultThe area of the square is 25
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• In the above example the derived class
  "Area" is derived from two base classes "Square"
  and "CShow". This is the multiple inheritance
  OOP's concept in C.

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Hierarchical Inheritance

• Explanation
• Hierarchical Inheritance is a method of
  inheritance where one or more derived classes is
  derived from common base class.

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Example

• include ltiostream.hgt
• class Side
• protected
• int l
• public
• void set_values (int x)
• lx
• class Square public Side
• public
• int sq()
• return (l l)
• class Cube public Side
• public int cub()
• return (lll)

int main () Square s s.set_values (10)
cout ltlt "The square value is" ltlt
s.sq() ltlt endl Cube c c.set_values (20) cout
ltlt "The cube value is" ltlt c.cub() ltlt
endl return 0
ResultThe square value is 100 The cube value
is8000
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• In the above example the two derived classes
  "Square", "Cube" uses
• a single base class "Side". Thus two
  classes are inherited from a single class. This
  is the hierarchical inheritance OOP's concept in
  C.

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Multilevel Inheritance

• Explanation
• Multilevel Inheritance is a method where a
  derived class is derived from another derived
  class.

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• include ltiostream.hgt
• class mm
• protected
• int rollno
• public
• void get_num(int a)
• rollno a
• void put_num()
• cout ltlt "Roll Number Is\n"ltlt rollno
  ltlt "\n"
• class marks public mm
• protected
• int sub1
• int sub2
• public
• void get_marks(int x,int y)
• sub1 x

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• void put_marks(void)
• cout ltlt "Subject 1" ltlt sub1 ltlt "\n"
• cout ltlt "Subject 2" ltlt sub2 ltlt "\n"
• class res public marks
• protected
• float tot
• public
• void disp(void)
• tot sub1sub2
• put_num()
• put_marks()
• cout ltlt "Total"ltlt tot

int main() res std1 std1.get_num(5)
std1.get_marks(10,20) std1.disp()
return 0
ResultRoll Number Is 5 Subject 1 10 Subject
2 20 Total 30
In the above example, the derived function "res"
uses the function "put_num()" from another
derived class "marks", which just a level
above. This is the multilevel inheritance OOP's
concept in C.
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Hybrid Inheritance

• Explanation
• "Hybrid Inheritance" is a method where one or
  more types of inheritance are combined together
  and used.

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• include ltiostream.hgt
• class mm
• protected
• int rollno
• public
• void get_num(int a)
• rollno a
• void put_num()
• cout ltlt "Roll Number Is"ltlt rollno ltlt
  "\n"
• class marks public mm
• protected
• int sub1
• int sub2
• public
• void get_marks(int x,int y)
• sub1 x

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• class extra
• protected
• float e
• public
• void get_extra(float s)
• es
• void put_extra(void)
• cout ltlt "Extra Score" ltlt e ltlt "\n"
• class res public marks, public extra
  
• protected
• float tot
• public
• void disp(void)
• tot sub1sub2e
• put_num()
• put_marks()
• put_extra()

int main() res std1 std1.get_num(10)
std1.get_marks(10,20) std1.get_extra(33.12)
std1.disp() return 0
ResultRoll Number Is 10 Subject 1 10
Subject 2 20 Extra score33.12 Total 63.12
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• In the above example the derived class "res"
  uses the function "put_num()". Here the
  "put_num()" function is derived first to class
  "marks". Then it is derived and used in class
  "res". This is an example of "multilevel
  inheritance-OOP's concept". But the class "extra"
  is inherited a single time in the class "res", an
  example for "Single Inheritance". Since this code
  uses both "multilevel" and "single" inheritance
  it is an example of "Hybrid Inheritance".

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The End of Lecture
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CONTACTS

• Mutaz Saeed mutelr_at_gmail.com
• mutelr_at_hotmail.com
• mutazko2000_at_hotmail.com