Inheritance in C#

Rushal Arora

14y3.7kVisual Basic .NET

Hi Everyone,

Please let me know the solution of below question :

Q.1) Need of Overriding?

Thanks and Regards

8 Replies

Know the answer? Post it — somebody with the same question will find it here.

Shivanand Arur14y ago
Accepted answer
Hello Rushal, Overriding is a feature where a Child Class can inherit its parent class and can use the methods of the Parent Class.

What is the use of Overriding???
Basically Overriding helps you to write less code by inheriting a parent class and "Reuse" the methods defined in the Parent class. For overriding a method, you first have to define the method in the Parent class with a "Virtual" keyword.

Now let me give you a simple example!!!

public class ParentClass()
{
public virtual void Walk()
{
          Console.WriteLine("The Object is walking");
}

public virtual void Run()
{
            Console.WriteLine("The Object is running");
}
}

Now a Human being can walk and run, let it be a male or a female. Even Animals walk and run. But the functioanlity of doing those things is different (2 legged Object(Man/Woman) and 4 legged Object(Animal))

public class Animal : ParentClass
{
public override void Run()
{
          Console.WriteLine("An Animal runs using its 4 legs");
}
}

So as you can see, the functionality changed but by using the Virtual and override keyword the Child Class can make use of the Parent Class's functions...

Hope this helps you out.

Please mark the answer as accpeted, if it helped!!!
Thank you!!!
Rushal Arora14y ago
My Title is C# and u have answered in VB.net, shall this make sense?
Satyapriya Nayak14y ago
In VB.net

Overriding: - It is the characteristics of the child or derived class, which overrides the characteristics of the parent class. The procedure in the base class, which could be overrides, is prefixed with the keyword Overridable. The procedure in the child class, which Overrides the base class procedure, is prefixed with the keyword overrides.

Mybase keyword is used in the child class to call the parent class procedure.

Program

Public Class Form2

    Dim a As New sagar1

    Dim b As New sagar2

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        MsgBox(a.amit(10, 20))

        MsgBox(b.amit(10, 20))

    End Sub

    Public Class sagar1

        Public Overridable Function amit(ByVal x As Integer, ByVal y As Integer)

            Dim z As Integer

            z = x + y

            Return z

        End Function

    End Class

    Public Class sagar2

        Inherits sagar1

        Public Overrides Function amit(ByVal x As Integer, ByVal y As Integer)

            Dim z As Integer

            z = MyBase.amit(x, y) * 5

            Return z

        End Function

    End Class

End Class

Thanks
Shivanand Arur14y ago
Hey Rushal, can U please mark any of the answer as accepted if it helped U. Thanks...
darma teja14y ago
Thanks vulpes
Vulpes14y ago
Darma,

If you remove the virtual and override keywords, then the Animal class's Run method is 'hiding' the ParentClass's Run method, rather than overriding it.

The difference is that, if an Animal object is assigned to a ParentClass variable and the virtual Run() method is called, then it will be Animal's version that is called, not ParentClass's. In other words, it's the actual type of an object, rather than the type of the variable, which is relevant when overriding a virtual method.

In contrast, if Run() were non-virtual but the scenario were otherwise the same, then it would ParentClass's version that was called because that is the type of the variable

This example illustrates the difference:

using System;

public class ParentClass
{
public virtual void Walk() // virtual
{
Console.WriteLine("The Object is walking");
}

public void Run() // non-virtual
{
Console.WriteLine("The Object is running");
}
}

public class Animal : ParentClass
{
public override void Walk() //overriding
{
Console.WriteLine("An Animal walks using its 4 legs");
}

public new void Run() // hiding - 'new' used to suppress compiler warning
{
Console.WriteLine("An Animal runs using its 4 legs");
}
}

class Test
{
static void Main()
{
ParentClass a = new Animal();
a.Walk();
a.Run();
Console.ReadKey();
}
}

The output is:

An Animal walks using its 4 legs
The Object is running
darma teja14y ago
Hi Shivanand,

I did your example without keyword "virtual" and "override" and it works.

Is it ok if i dont use "virtual" and "override" keywords in overriding.

Darma
Santhosh Kumar Jayaraman14y ago
Take this example.. There is a parent class called shape. it has some methods such as calculatearea and calculateVolume. And it has some method implementation.

Now when you have child class circle, it will also has same method, but the implementation i.e formula/calculation will be different. Similarly for sphere, square. So there will be a common method calcualte area for most of the shapes, but for some of the child classes can have their own area calculation logic. So we need to go for overriding.

Inheritance in C#

Program