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WELCOME. TO. Object oriented programming with C#.NET. Features of Object Oriented Programming:. Any programming language to become as object oriented should follow the following features. Abstraction Encapsulation Inheritance Polymorphism. What is an Abstraction?.

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welcome
WELCOME

TO

Object oriented programming with C#.NET

features of object oriented programming
Features of Object Oriented Programming:

Any programming language to become as object oriented should follow the following features.

  • Abstraction
  • Encapsulation
  • Inheritance
  • Polymorphism
what is an abstraction
What is an Abstraction?
  • It’s a process of Hiding the Implementation but providing the service.
  • There are two types of abstraction available:
  • Data Abstraction
  • Functional Abstraction

What is an Encapsulation?

  • It is a process of Binding the member variable of a class along with member functions.
  • Encapsulation can be implemented with the help of object and also Access modifiers like Private ,public and Protected etc.
what is an inheritance
What is an Inheritance?
  • This is process of creating a new class from already existing class
  • In inheritance process existing class is known as Parent/Base class, newly created class is know as Derived/Child class.
  • In inheritance process, child class will get all the features of Parent/Base class.
  • Main purpose of inheritance is code Re-usability and providing additional functionality/enhancement.
what is polymorphism
What is Polymorphism?
  • It’s derived from a Greek word, where poly means many morph means Faces/Behaviors.
  • Types of Polymorphism:
  • There are two types of polymorphism
  • Static polymorphism/Compile Time polymorphism /Early Binding
  • Dynamic polymorphism/Run Time polymorphism/late Binding
  • Static polymorphism is achieved using, Function over loading, operator over loading.
  • Dynamic polymorphism is achieved by using , Function overriding.
class in c net
Class in C# .NET
  • A class is a collection of things which posses common similarities.
  • In C#.NET a class is a user defined Data type and is Known as Reference Type.
  • A class can contain following members in C#.NET

Data Fields

Function

Constructors

Destructors

Properties

Indexers

Events

1 data fields
1.Data Fields
      • It’s used to store the data related to the class.
  • Except Data Fields no other member of a class can store the data.
  • To declare any Data Field, we use the following

Syntax

Access modifier Data type Data Field Name = [Initializing value];

Ex:Public int Empid;

2 functions
2.Functions
  • Any programming language will have methods.
  • A named block of code is refer as a Method or subprogram.
  • It can be either value returning or non value returning.

Syntax

[]([

{

statements;

};

syntax to create a class
Syntax to create a class

Access Modifier class Class Name

Syntax to create an Object

Ex: Program p= new program() or

Program p;

P=new program();

Class Name Object Name=new Class Name([args list])

Constructor name

how to open microsoft visual studio net
How to open Microsoft visual studio .NET

Open V.S Go to File New project Change the language as C# template as Console application Named return as OOPS Project and the write the following code under the default class program

Class program

{

//No input and out put

Void Text1 ()

{

Console.WriteLine (“first method”);

}

slide11
// No output but has Input Void Text2 (int x, int y) { For (int i=1;i<=y;i++)Console.writeLine (“{0} *{1}={2}”;x, i, x*i); }//No Input but has out put String Text3 (){Return “third method”;}//has input and out putString text4 (string name){return “Hello” +name;}
slide12
//Method with Multiple output parameters

Void Meth1 (int x, int y, ref int a, ref int b)

{

a=x+y;

b=x/y;

}

Static VoidMain (string [] args)

{

Program p=new program ();

p.Text1 (); p.Text2 (5, 10);

Console.WriteLine (p.Text3 ());

Console.WriteLine (p.Text4 (“venkat”));

Int m=0, n=0; //Initialization is mandatory

p.Math1 (100, 50, ref m, ref n);

Console.WriteLine (M+” “+n);

Int q, r; //Initialization is optional

p.Math2 (100, 50, out q, out r);

Console.WriteLine (q+” “+r);

Console.Readline ();

}

}

slide13
Constructors
  • A constructor is a member method of a class which is invoked automatically when an object to the class is created.
  • A constructor name should be same name as class name .
  • A constructor does not have any return type even void also.
  • A constructor is used to keep something ready for the object when it is created .

Syntax

[]([])

{

Statements;

}

slide14
Example program

Add a class ConDemo.cs and write the following code

Class ConDemo

{

ConDemo ()

{

Console.WriteLine (“Constructor”);

}

Void Demo ()

{

Console.writeLine (“Method”);

}

Static VoidMain ()

{

ConDemo cd1=new ConDemo ();

ConDemo cd2=new ConDemo ();

ConDemo cd3=cd2;

Cd1.Demo (); cd2.Demo (); cd3.demo ();

Console.ReadLine ();

}

}

slide15
Constructors are TWO Types

1

Default Constructor

2

Parameterized Constructor

  • A constructor without any parameters is a “Default constructor” which can be defined either by the programmer or will be defined by the compiler provided the class doesn't contain any constructor in it.
  • A constructor with parameters is referred as “parameterized constructor” which can be defined only by a parameters.
  • If at all constructors are parameterized we can send values to the parameters at the time of object creation.
slide16
Example program

Add a class Maths.cs and write the following code

Class Maths

{

Int x, y; //class variables

Maths (int x, int y ) //block variables

{

This.x=x;

This.y=y;

}

Void Add ()

{

Console.WriteLine(x+y);

}

Void Sub()

Console.WriteLine(x-y);

}

Void Mul ()

{

Console.WriteLine(x*y);

}

slide17
Void Div ()

{

Console.WriteLine(x/y);

}

Static VoidMain ()

{

Maths m=new Maths (100, 50);

m.Add ();

m.Sub () ;

m.Mul();

m.Div();

Console.ReadLine ();

}

}

slide18
Inheritance
  • The process creating a new class form already existing class.
  • Existing class is known as Parent Class or Base Class.
  • New class is known as Child Class or Derived Class.
  • Child class will get all the features of parent class
  • Code Reusability and providing additional functionalities

class1

members

Parent child Relation

consume

slide19
Syntax

Child Class

Parent Class

[] class :

Class Class1

{

Members

}

Class Class2 : Class1

{

Consume the parent members here

}

slide20
Example program

Add a class class2.cs and write the following code

Class class2:class1

{

Public class2 ()

{

Console.writeLine (“class 2 constructor”);

}

Public void Text3 ()

{

Console.writeLine (“Method Three”);

}

Static VoidMain ()

{

Class2 c=new class2 ();

c.Text1 ();

c.Text12 ();

c.Text3 ();

console.Readline ();

}

}

Add a class class1.cs and write the following code

Class class1

{

Public class1 ()

{

Console.WriteLine (“class1 constructor”);

}

Public void Text 1()

{

Console.writeLine (“Method one”);

}

Public void Text2()

{

Console.WriteLine (“Method Two”);

}

}

slide21
Polymorphism
  • Over Loading
  • Polymorphism can be implemented with the help of TWO approaches
  • Overriding

Same name different signatures are called overloading method

Same name and same signature is called overriding method

slide22
Example program

Public void show (int x, string s)

{

Console.WriteLine (4);

}

Public void show (string s, int x)

{

Console.WriteLine (5);

}

Static VoidMain ()

{

Load demo obj =new LoadDemo ( );

Obj. Show (10);

Obj. show (“Hello”);

Obj. Show (10,”Hello”);

Obj. Show (“Hello”, 10);

Console.Readline ();

}

}

}

Add a class Load demo.cs and write the following code

Class LoadDemo

{

Public void show ()

{

Console.WriteLine (1);

}

Public void show (int x)

{

Console.WriteLine (2);

}

Public void show (string s)

{

Console.WriteLine (3);

}

slide23
Properties
  • A property is a member of a class , used to write the data in the data field and read the data from the data field of a class.
  • A property can never store the data, just used to transfer the data.
  • Properties are members that provide a flexible mechanism to read, write or compute the values of private fields.
  • Properties enable a class to expose a public way of getting and setting values, while hiding implementation or verification code.
  • To perform read and write operations, property can contain two assessors/methods.
slide24
Assessors with in the property
  • Accessor enable data to be accessed easily while still providing the safety and flexibility of methods.
slide25
Set accessor is used to write the data into the data field.
  • This will contain a default and fixed variable named as “value”.
  • Whenever we call the property to write the data, any data we supply will come and store in value variable by default.

Set Accessor

Syntax

Set

{

Data File Name=value;

}

Get

{

Return Data File Name:

}

Get Accessor is used to read the data field, using this accessor we can’t write the data.

Get Accessor

slide26
Types of properties
  • C#.NET will support three types of Properties.
  • This property is used to read the data from the Data field
  • It is used to write the data into Data field of a class.
  • It is used to read the data from the Data field and to write the data in to the Data Field

Access Modifier Data Type property Name

{

set

{

Data Field Name=Value;

}

}

Access Modifier Data Type Property Name

{

get

{

return data Field Name;

}

}

slide27
Syntax

Example

Namespace CAProperties

{

Class clsEmpolyee

{

int EmpId,EAge;

Public int PEmpId

{

set

{

EmpId=value;

}

get

{

return EmpId;

}

}

Access Modifier Data Type property Name

{

set

{

Data Field Name=Value;

}

get

{

return data Field Name;

}

}

slide28
Public int PEAge

{

set

{

EAge=Value;

}

get

{

return EAge;

}

}

}

Class ClsProperty1

{

Static void Main(string[] args)

{

clsEmployee obj1=new clsEmployee();

Console.write(“Enter Employee details:”);

Obj1.PEmpId=Concert.ToInt32(Console.ReadLine());

Obj1.PEAge=convert.ToInt32(console.ReadLine());

}

}

}

slide29
Abstract
  • It is a method with can have only syntax, but no implementation is called Abstract Method.
  • It should be overridden in the Sub Class.
  • It can be used mostly in Distributed Applications (Client/sever applications)

Syntax

AccessSpecifier abstract Return Type Method Name(parameters);

Public abstract void Hello();

Example

slide30
Interfaces
  • In the .NET Framework, interfaces have a special naming convention. All interface name begin with a capital I. Interfaces can have properties as we difference from a class.
  • You cannot create an object of an interface
  • An interface does not contain any constructor.
  • All methods in an interface are abstract.
  • An interface can inherit multiple interfaces.

[] interface

{

Abstract member declarations

}

Syntax

slide31
Add an interface inter1.cs and write the following code

Interface inter1

{

Void Add (int x, int y);

Void sub (int x, int y);

Void test ();

}

}

Add an interface inter2.cs and write the following code

Interface inter2

{

Void Mul (int x, int y);

Void Div (int x, int y);

Void test ();

}

}

To implement both the above two interfaces

Add a class interclass.cs and write the following code

Class Interclass: Inter1, Inter2

{

Public void Add (int x, int y)

{

Console.Writeline(x+y);

}

Public void Sub (int x, int y)

{

Console.Writeline(x-y);

}

Public void Mul (int x, int y)

{

Console.Writeline(x*y);

}

slide32
Public void Div (int x, int y)

{

Console.Writeline(x/y)

}

public void Test ()

{

Console.Writeline (“Declared under multiple interfaces”);

}

Void Inter1.Test ()

{

Console.Writeline (“Method of Interfaced 1”);

}

Void Inter2.Test ()

{

Console.Writeline (“Method of Interfaced 2”);

}

Static Void Main ()

{

Inter class obj= new Inter class ();

Obj. Add (100, 45);

Obj. Sub (100, 45);

Obj. Mul (100, 45);

Obj.Div (100, 45);

Obj. Test ();

Inter1 i1 = obj; Inter i2 = obj;

I1.Test (); i2.Test ();

Console.ReadLine ();

}

}

slide33
Delegates
  • It’s used to represent or refer one or more functions.
  • Delegates are user defined types in C#.NET.
  • Delegates in C#.NET are similar to function pointers in C++.
  • It is not a member of a class, but similar to a class.
  • To consume any delegate , we need to create an object to delegate. Delegate is a type that references a method.
  • The delegate method can be invoked like any other method with parameters and written value.
  • These can be used to define callback methods.
  • There are the backbone for events.
slide34
Types of Delegates
  • There are of two types of Delegates available.
  • Single cast delegate
  • Multi cast delegate
  • A delegate that represents only function is known as Single Cast Delegate.
  • A delegate that represents only a more than one functions is known as Multi Cast Delegate.
  • To work with Delegate Use the Following Steps:
  • Creating a Delegate
  • Instantiating a Delegate
  • Invoking a Delegate
slide35
EX:
  • If we consider a function, like
  • Public Void Add (int a , int b )
  • {
  • Code……
  • }
  • To refer this function, if we want to use the Delegate, we use the following steps like…..

STEP 1

Creating A Delegate

Syntax

Access modifier delegate return type Delegate name([arguments list])

EX: public delegate void sampleDelegate(int x, int y)

slide36
Instantiating a Delegate

STEP 2

Delegate name object name = new Delegate name (Target function name);

Syntax

EX: SampleDelegate obj=new SampleDelegate(Add);

Invoking a Delegate

STEP 3

Syntax

Object Name([Arguments Values])

EX: Obj(10,20)

slide37
Add a class del.cs and write the following the code

Class Delclass

{

Public String SayHello(string name0

{

Return “Hello” +name;

}

Public delegate string SayDel(String name);

Static void Main()

{

Delclass obj=new Delclass();

SayDelSd=new SayDel(obj.sayHellow);

Console.WriteLine(Sd(“xxx”));

Console.WrireLine(Sd(“yyy”));

Console.WrireLine(Sd(“zzz”));

Console.ReadLine();

}

}

Program

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