C# 0 The Complete Reference

MyExtMeths

. As explained, an extension method must be declared within a static class. 

Furthermore, this class must be in scope in order for the extension methods that it contains 

to be used. (This is why you needed to include the 

System.Linq

 namespace to use the LINQ-

related extension methods.) Next, notice the calls to the extension methods. They are 

invoked on an object, in just the same way that an instance method is called. The main 

difference is that the invoking object is passed to the first parameter of the extension 

method. Therefore, when the expression

val.AbsDivideBy(-2)

executes,