Ø  Abstraction and encapsulation are important features of any object-oriented programming language.

Ø  Abstraction involves extracting only the relevant information.

Ø  Encapsulation literally means ‘to enclose in or as if in a capsule’.

Ø  Encapsulation is defined as the process of enclosing one or more items within a physical or logical package.

Ø  It involves preventing access to nonessential details.

Ø  An access specifier defines the scope of a Class member.

Ø  A class member refers to the variables and functions in a class.

Ø  A program can have one or more classes.

Ø  You may want some members of a class to be accessible to other classes.

Ø  But, you may not want some other members of the class to be accessible outside the class.

Ø  C# supports the following access specifiers:

v  public

v  private

v  protected

v  internal

v  protected internal

ØA method is a set of one or more program statements, which can be executed by referring to the method name.

ØTo use methods, you need to:

v  Define methods

v  Call methods

Ø  Defining a method means declaring the elements of its structure.

Ø  Consider the syntax of defining a method:

(Parameter List)

{

                Method Body

}

Ø  The elements of the method declaration include the method name, the Parameters list, the return type, and the method body.

Ø  The following are the elements of a method:

v  Access specifier:  This determines the extent to which a variable or method can be accessed from another class.

v  Return type: A method can return a value of any type. If the method is not returning any value, use void as the return type.

v  Method name : is unique. It cannot be the same as the variable name or any other
non-method item declared in the class.

v  Parameter list : is used to pass and receive the data from a method. It is enclosed between parentheses. The parentheses are included even if there are no parameters.

v  Method body :It contains the set of instructions needed to complete the required activity.

Ø  After defining the method, you can execute it by calling it.

Ø  You can call a method by using the name of the method.

Ø  The method name is followed by parentheses even if the method call has no parameters, as shown in the following example:

MethodName();

eg:- Class Demo

{

public void display()

                {

                Console.WriteLine(“Hello World”);

                }

                                public static void main(String [] args)

{

Demo obj=new Demo();

obj.display();

}

 }

Ø  Methods can also be declared with parameters. Consider the example of declared a method with parameters:

void DisplayResult (int result)

{

//…..

}

Ø  When the methods are declared with parameters, they should be called with parameters. The methods with parameters are called by passing the value using the following mechanism:

v  Value

v  Reference

v  Output

Ø  Value: The Parameters Passed by value creates a separate copy in the memory. The following example shows the parameters passed by value:

void Sum( int num1, int num2)

{

//…        

}

void Accept()

{

int val1=10;

int val2=2;

Sum(val1,val2);

}

Ø  Reference: The parameters passed by reference does not creates a separate copy of the variable in the memory. A reference parameter stores the memory address of the data member passed. The following example shows the parameters passed by reference:

void Sum( ref int num1,ref int num2)

{

                //…        

}

void Accept()

{

                int val1=10;

                int val2=2;

                Sum( ref val1,ref val2);

}

Ø  Output: The output parameters are used to pass the value out of the method. The following example shows the parameters passed by reference:

void Sum( ref int num1,ref int num2, out int result)

{

result=num1+num2;     

}

void Accept()

{

                int val1=10;

                int val2=2;

                int recieveVal;

                Sum( ref val1,ref val2,out recieveVal);

}