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Interface in .Net

Interface in .Net

SIVA

SIVA

12y1.5kLearn iOS Programming

Team,

As I know that we can't create instance for Interface in .Net

But, I m bit confuse with some scenario's like,

Interface IA

{

add();

}

Class A : IA

{

add()

{

}

}

Now,I can use

IA obj = new A()

Can you please explain briefly & give some reference links to understand with core.

Thanks

4 Replies

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SIVA12y ago
Ranjit, Same question is not answer for that. Please understand the question properly and answer. Thanks
SIVA12y ago
Thanks Vulpes
Vulpes12y ago
Although you can't create instances of an interface, you can declare variables and parameters of the interface type.

You can assign to such variables or parameters instances of classes or structs which implement the interface.

So in your example code, you have this line:

IA obj = new A();

which declares a variable, obj, of the interface type IA and then assigns to it an instance of the class A which implements IA.

Because we know that any class (or struct) which implements IA must have a public add method, we also know that we can do this:

obj.add();

In general, you can only call those methods of A which implement the IA interface through the variable obj. The variable doesn't know anything about other methods or properties which A may contain.

The purpose of allowing variables and parameters of interface types is to allow you to write generic code in relation to any class or struct which implements the interface even those those types may otherwise have no relation to each other.

For more on interfaces, check out this link:

http://msdn.microsoft.com/en-us/library/ms173156.aspx
Ranjit Powar12y ago
Try this

interface I1
    {
      void add();
    }
    class Program:I1
    {
        public void add()
        {
            Console.Write("Hi");
        }
        static void Main(string[] args)
        {
            I1 i = new Program();
            i.add();
        }
    }