Question

Implementing Interface just provide the skeleton of the method. If we know the exact signature line of that method, in this case
what is the requirement to implement Interface?
This is the case in which Interface has been implemented

interface IMy
{
    void X();
}
public class My:IMy
{
    public void X()
    {
        Console.WriteLine("Interface is implemented");
    }
}

This is the case in which Interface has not been implemented

public class My
{
    public void X()
    {
        Console.WriteLine("No Interface is implemented ");
    }
}

My obj = new My();
obj.X();

Both the approaches will produce the same result.
what is the requirement to implement Interface?

Answer 1

There are two purposes of inheritance in .net:

1. Allow derived classes to share the base-class implementations of common functionality
2. Allow derived-class objects to be substituted for base-class objects anywhere the latter would be accepted.

Unlike some languages (C++, for example) which allow multiple inheritance, .net requires every class to have precisely one parent type (Object, if nothing else). On the other hand, sometimes it’s useful to have a class be substitutable for a number of unrelated types. That’s where interfaces come in.

An object which implements an interface is substitutable for an instance of that declared interface type. Even though objects may only inherit from one base type, they may implement an arbitrary number of interfaces. This thus allows some of the power of multiple inheritance, without the complications and drawbacks of full multiple-inheritance support.