C# and .NET interview questions: Explain an interface?

Answer: 

Interface is a contract that defines the signature of the functionality.
So if a class is implementing a interface it says to the outer world, that
it provides specific behavior. Example if a class is implementing
‘Idisposable’ interface that means it has a functionality to release
unmanaged resources. Now external objects using this class know that it has contract by which it can dispose unused unmanaged objects.

  • Single Class can implement multiple interfaces.
  • If a class implements a interface then it has to provide
    implementation to all its methods.

Following code shows that one has the interface definition and other
class implements the interface. Below is the source code “IInterface” is the interface and “ClsDosomething” implements the “IInterface”. This sample just displays a simple message box.

Public Interface IInterFace
Sub Do Something ()
End Interface

Public Class ClsDoSomething
Implements IInterFace
Public Sub DoSomething () Implements WindowsInterFace.IInterFace.DoSomething
MsgBox (“Interface implemented”)
End Sub
End Class

After implementing the above code you will get the following output as
shown:

Following you can see a simple video on boxing and unboxing:


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Regards,

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About c# and .NET Interview questions

This blog is for developers who want to crack .NET and C# interviews. It has all tips and tricks needed to crack .NET interviews , C# interview , SQL Server interview , Java interview , WCF Interview , Silverlight interview , WPF interview , LINQ interview , Entity framework Interview. Do not forget to watch our Learn step by step video series. Learn MVC in 16 hours:- https://www.youtube.com/watch?v=Lp7nSImO5vk Learn AngularJS Step by Step:- https://www.youtube.com/watch?v=0kmdjqgO9IY Learn Design Pattern in 8 hours:- https://www.youtube.com/watch?v=YDobmucohqk Learn C# and .NET in 60 days:- https://www.youtube.com/watch?v=yh2SrzCkNQA Learn MSBI in 32 hours:- https://www.youtube.com/watch?v=mGPJx3ocFgg Learn SharePoint Step by Step in 8 hours:- https://youtu.be/C2fW76SwJNU
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