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Oops concept on c#
2. Disclaimer: This presentation is prepared by trainees of
baabtra as a part of mentoring program. This is not official
document of baabtra –Mentoring Partner
Baabtra-Mentoring Partner is the mentoring division of baabte System Technologies Pvt .
Ltd
6. POP OOP
In POP, program is divided into small parts
called functions.
In OOP, program is divided into parts
called objects.
POP does not have any proper way for
hiding data so it is less secure.
OOP provides Data Hiding so
provides more security.
Example of POP are : C, VB, FORTRAN,
Pascal.
Example of OOP are : C++, JAVA, VB.NET,
C#.NET.
7. Oops Concept in C#
• Object Oriented Programming
language(OOPS):-
It is a methodology to write the program
where we specify the code in form of classes
and objects.
8. Class
• Class is a user defined data type. it is like a
template. In c# variable are termed as instances
of classes. which are the actual objects.
Class classname
{
variable declaration;
Method declaration;
}
9. Object
• Object is run time entity which has different attribute to identify it
uniquely.
Rectangle rect1=new rectangle();
Rectangle rect1=new rectangle();
Here variable 'rect1' & rect2 is object of the rectangle class.
The Method Rectangle() is the default constructor of the class. we
can create any number of objects of Rectangle class.
10. Basic Concept of oops:-
• There are main three core principles of any
object oriented languages.
• INHERITANCE
• POLYMORPHISM
• ENCAPSULATION
11. INHERITANCE:-
• One class can include the feature of another
class by using the concept of inheritance.In c#
a class can be inherit only from one class at a
time.Whenever we create class
that automatic inherit from System.Object
class,till the time the class is not inherited
from any other class.
12. • class BaseClass
• {
• //Method to find sum of give 2 numbers
• public int FindSum(int x, int y)
• {
• return (x + y);
• }
• //method to print given 2 numbers
• //When declared protected , can be accessed only from inside the derived class
• //cannot access with the instance of derived class
• protected void Print(int x, int y)
• {
• Console.WriteLine("First Number: " + x);
• Console.WriteLine("Second Number: " + y);
• }
• }
13. • class Derivedclass : BaseClass
• {
• public void Print3numbers(int x, int y, int z)
• {
• Print(x, y); //We can directly call baseclass
members
• Console.WriteLine("Third Number: " + z);
• }
• }
14. • class Program
• {
• static void Main(string[] args)
• {
• //Create instance for derived class, so that base class members
• // can also be accessed
• //This is possible because derivedclass is inheriting base class
• Derivedclass instance = new Derivedclass();
• instance.Print3numbers(30, 40, 50); //Derived class internally calls base class method.
• int sum = instance.FindSum(30, 40); //calling base class method with derived class instance
• Console.WriteLine("Sum : " + sum);
• Console.Read();
• }
•
• }
15. • Output:-
• First number:30
• Second number:40
• Third number:50
• Sum:70
16. ENCAPSULATION:-
• Encapsulation is defined 'as the process of enclosing one or more
items within a physical or logical package'. Encapsulation, in object
oriented programming methodology, prevents access to
implementation details.
• Abstraction and encapsulation are related features in object
oriented programming. Abstraction allows making relevant
information visible and encapsulation enables a programmer
to implement the desired level of abstraction.
• Encapsulation is implemented by using access specifiers. An access
specifier defines the scope and visibility of a class member. C#
supports the following access specifiers:
• Public
• Private
• Protected
17. POLYMORPHISM:-
• It is also concept of oops. It is ability to take more than
one form. An operation may exhibit
different behaviour in different
situations.
• C# gives us polymorphism through inheritance.
Inheritance-based polymorphism allows us to define
methods in a base class and override them with
derived class implementations
• You can have multiple definitions for the same function
name in the same scope. The definition of the function
must differ from each other by the types and/or the
number of arguments in the argument list.
20. Override
• class Color
• {
• public virtual void Fill()
• {
• Console.WriteLine("Fill me up with color");
• }
• public void Fill(string s)
• {
• Console.WriteLine("Fill me up with {0}", s);
• }
• }
• class Green : Color
• {
• public override void Fill()
• {
• Console.WriteLine("Fill me up with green");
• }
• }
• class nab
• {
• static void Main()
• {
• Green c1 = new Green();
• c1.Fill();
• c1.Fill("red");
• Console.Read();
• }
•
• }
• Out put:
• Fillup with Green
• Fillup with Red
21. Dynamic Polymorphism
• C# allows you to create abstract classes that are used
to provide partial class implementation of an interface.
Implementation is completed when a derived class
inherits from it. Abstract classes contain abstract
methods which are implemented by the derived class.
The derived classes have more specialized
functionality.
• Please note the following rules about abstract classes:
• You cannot create an instance of an abstract class
• You cannot declare an abstract method outside an
abstract class
• When a class is declared sealed, it cannot be inherited,
abstract classes cannot be declared sealed.
22. • abstract class Shape
• {
•
• public abstract int area();
•
• }
• class Rectangle: Shape
• {
• private int length;
• private int width;
• public Rectangle( int a, int b)
• {
• length = a;
• width = b;
• }
• public override int area ()
• {
• Console.WriteLine("Rectangle class area :");
• return (width * length);
• }
• }
• class RectangleTester
• {
• static void Main(string[] args)
• {
• Rectangle r = new Rectangle(10, 7);
• double a = r.area();
• Console.WriteLine("Area: {0}",a);
• Console.ReadKey();
• }
• }
• Out put:
• Rectangle class area :
• Area:70
23. Abstract Classes and Class Members
• The purpose of an abstract class is to provide a
common definition of a base class that multiple
derived classes can share. For example, a class library
may define an abstract class that is used as a
parameter to many of its functions, and require
programmers using that library to provide their own
implementation of the class by creating a derived class.
• Abstract classes may also define abstract methods. This
is accomplished by adding the keyword abstract before
the return type of the method. For example:
24. sealed
• When applied to a class, the sealed modifier
prevents other classes from inheriting from it.
• When you define new methods or properties
in a class, you can prevent deriving classes
from overriding them by not declaring them
as virtual.
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