Why is adding null to a string legal?

Question

The MSDN article on String Basics shows this:

string str = \"hello\";
string nullStr = null;
string emptyStr = \"\";

string tempStr = str + nullStr; // temp         


        

Answer 1

I agree that conceptually strings are just values. However, consider the following code:

int? i = null;
i += 1; // The result of this is that i == null

If the other value type operators used default() the way the string operators are converting null to "", your explanation would make sense.

It's simplest to say that the string operators are a shortcut (special case) for convenience.