009 C# tutorial Method Part 2

Method can be declared with various access specifier, here are the name of access specifier which

 method can be declare. 

• Public 
• Private 
• Protected

Here are the example of method access specifiers. 

 

Example of Public 

 public class Student

  {

          public double CalculateFees()

         {

          double d = 10.00;

           return d;

          }

}

// Mehod Calling

Student obj = new Student();

double fees = obj.CalculateFees();

Example of Private

public class Student

{

          private double CalculateFees()

          {

             double d = 10.00;

             return d;

           }

}

// Mehod Calling

Student obj = new Student();

double fees = obj.CalculateFees();//error inaccessable due to protection level

 Example of Protected

 public class Student

 {

         public void CalculateFees()

         {

         Method2();

        }

        protected virtual void Method2()

       {

        Console.WriteLine("I am at student level");

     }

}

public class Child : Student

{

      protected override void Method2()

       {

      Console.WriteLine("I am at child level");

      }

}

// Mehod Calling

var b = new Student();

b.CalculateFees(); // returns "I am at student level"

var d = new Child();

d.CalculateFees(); // returns "I am at child level"

Sealed : Method signature also define a method behaviour in an application. Can be sealed,

 who is prevent method from inheritance to child object. Here is the example of method signature 

protect method from being inherit. 

Example 1

sealed class Student

{

}

Example 2  

class Student

{

          sealed override public void GetFees()

          {

           Console.WriteLine("In class B");

         }

}

class Child : Student

{

           override public void GetFees()

          {

           //Error 1 'Student.GetFees()': no suitable method found

         //Error 2 'Child.GetFees()': cannot override inherited member 'Student.GetFees()

         }

}

Async Method : A method is a statement to do some work, but while a method is doing his work all 

other work of the application stopped, async method is a kind of method which does not force 

the application to stop the other work. While async method is called, other work also possibles 

simultaneously the application, program can run other statement also while async methods running.

 Here is the example of async method. 

Example 1  

public static async Task asyncMethod()

{

      await Task.Run(() =>

       {

          for (int i = 0; i < 100; i++)

         {

         Console.WriteLine(" asyncMethod ");

         }

       });

}

Now we will discuss some advanced topics about an method and its applications. The fast topics

 we will discuss parameter array. 

Parameter Array : If method is called a parameter type of array, the whole copy of array copied into 

the original method. The array can be any type integer, string, Boolean. A Method can also return array,

 to return a method array type, we need to be configure method return type error type. 

Example 1

//Method calling

int[] roll = new int[] { 1, 2, 3 };

PassArayMethod(roll);

Response.Write(roll[0]);

//out put:45

//Method declaration

public void PassArayMethod(int[] data)

{

data[0] = 45;

}

Example 2

static int[] ArrayReturnMethod(int l)

{

         int[] arr = new int[l];

        for (int a = 0; a < l; a++)

       {

          arr[a] = 5 * a;

        }

      return arr;

}

//Method calling

int[] roll = ArrayReturnMethod(6);

Response.Write(roll[0]);

Response.Write(roll[1]);

Response.Write(roll[2]);

Response.Write(roll[3]);

//out put:0

//out put:5

//out put:10

//out put:15

Method Overloading : Overloading easy concept of object oriented programming which call the 

method depending upon the parameter passing. We can declare a number of same name method

 in an object. That means, we can define multiple method with same name, but the parameter 

should be different in each case. When we call the method, the compiler make the appropriate match

 of definition with calling program. When appropriate match definition is found compiler call this

 method. This functionality call method overloading. Here are the example of method overloading. 

 Example 1

class Student

{

            public string GetFees()

          {

            return "Method with Zero Argumant";//code ignored

          }

          public string GetFees(int roll_number)

         {

          return "Method with Single Argumant";//code ignored

         }

         public string GetFees(DateTime dateOfBirth, string Name)

        {

         return "Method with Double Argumant";//code ignored

       }

}

//Method calling

Student obj = new Student();

Response.Write(obj.GetFees()+ "
");

Response.Write(obj.GetFees(123)+ "
");

Response.Write(obj.GetFees(DateTime.Today,"John")+ "
");

//out put:Method with Zero Argumant

//out put:Method with Single Argumant

//out put:Method with Double Argumant

Here are some interview related question. 

1)What can you specify the accessibility modifier for method inside the interface?  

Method declared under an interface is by default public. We cannot declare at them private, protected

 or any modifier rather than public. 

2)Can you declare an override method static if the original method is not static? 

No, the overriding method and the original method should have the same signature and access 

specifier. 

3)Can you allow a class to be inherited, but prevent method being overridden? 

If I declare a class public, the class will be access from anywhere in the application. 

Now I am declaring a method with signature field. Now the class will be available for generations

 but the method will not be inherited. 

4)Can we define method overloading in different class? 

Method overloading can be possible only in the same class and structure.

 If we define same name method in define classes, that will not act as a method overloading.

 Every object instance is created with his own method and calling this method with object instance

 have no interaction effect with each other. 

5)Can you prevent private Virtual method?  

Private Virtual method cannot be access. 

6)Static method cannot use static member, the statement is true or false? 

True