Extension Methods

Question

http://www.c-sharpcorner.com/UploadFile/puranindia/extension-methods-in-C-Sharp-3-0/

In above web page Extension Methods is explained.

Can you tell me please where I can find ClassLibExtMethod.dll file? As directed in the article to "Add the reference of the previously created class library to this project".

I couldn't see any ClassLibExtMethod.dll file in ClassLibExtMethod folder.

I use VS 2012 Express.

Vulpes · Answer

If you just want to learn how to write an extension method then put all the code in the exe - don't bother with the dll: using System; using System.Text; using ClassLibExtMethod; namespace ClassLibExtMethod { public class Class1 { public string Display() { return (I m in Display); } public string Print() { return (I m in Print); } } } namespace ExtensionMethod1 { public static class XX { public static void NewMethod(this Class1 ob) { Console.WriteLine(Hello I m extended method); } } class Program { static void Main(string[] args) { Class1 ob = new Class1(); Console.WriteLine(ob.Display()); // altered this line Console.WriteLine(ob.Print()); // ditto ob.NewMethod(); Console.ReadKey(); } } } I've had to alter the code in the Main method slightly to get it to print the same output as in the article.

Abhishek Singh · Answer

Hi Maha You need to create a new Class Library project named ClassLibExtMethod as explained in the article. After building successfully dll will be created and you can use that .dll in your project. Hope this make it clear. Abhishek

Maha · Answer

Thank

Vulpes · Answer

They're called extension methods because they extend the methods which are provided by the class struct or interface itself i.e. the type of the 'this' parameter. Although they're really just static methods (and can be called as such if you want) they're made to look as though they're instance methods of the type in question.

Maha · Answer

You have made the matter easy. Thank you for your help. Quoting your example please explain why it is called extended method.

Maha · Answer

No I am very sure I selected Class Library. You can see this in my attachment (picture in 3rd thread).

Pradeep Shet · Answer

Hi Maha While creating the project you have not selected Class Library. I guess you have selected ConsoleApplication. Thats the reaso n dll didn't got generated. Mark it answered if it is so.

Maha · Answer

Bin-> debug folder is empty

Abhishek Singh · Answer

You need to go to Bin-> debug folder then you will able to see the dll created after successful build.

Maha · Answer

I have already created ClassLibExtMethod folder but I couldn't see any ClassLibExtMethod.dll file in it. I attach what is in ClassLibExtMethod folder.