Documenting the extension methods in C #

extension methods in C #.

1. System comes with the type, we can not go to modify;
2. It takes a lot of effort to modify the source code and may cause errors;
3. We just need a few or fewer ways to modify the source code is time consuming and laborious;
4. The extended class is sealed and cannot be inherited; (even if it's not sealed, we can't write a subclass because we need a method, so it's not object-oriented)

Three elements of an extension method:

1. The extension method must be in a static class;
2. The extension method must be a static method;
3. The argument list of an extension method must begin with this, followed by the extension class, and then the parameter required by the method;

Documenting the extension methods in C #