C # If the value of an object is null, then why does it not give an error when it calls the extension method

If the value of an object is null, does it give an error when calling an extension method?

Person p = null;p. Extendmethod ();

The above code will not be an error, the beginning of this situation is very puzzled, asked Daniel. Daniel explains the following:

The extension function is only intended to make the code more readable, but it will eventually be translated into a standard static function call in the CLR.

Like what:

public static void Extmethod (This string str) {    if (!string. IsNullOrEmpty (str))    {         //For str processing          }    }

Call "string". Extmethod () will eventually be translated into Extmethod ("string"); So even if it's null, it won't be an error.

Null why can't I point out the extension function?

Obtain its own method by NULL as follows:

　　

Try this ((string) null). Extmethod () must be able to point it out.

　　

The key is to use the extension function to see the corresponding data type.

C # If the value of an object is null, then why does it not give an error when it calls the extension method