Use of “this” keyword in formal parameters for static methods in C#

Question

I\'ve come across several instances of C# code like the following:

public static int Foo(this MyClass arg)

I haven\'t been able to find an

Answer 1

"this" extends the next class in the parameter list

So in the method signature below "this" extends "String". Line is passed to the function as a normal argument to the method. public static string[] SplitCsvLine(this String line)

In the above example "this" class is extending the built in "String" class.