Does At symbol (@) and Dollar Sign ($) has any special meaning in C or C++

Question

Recently one of my friend encountered this question in an interview. The interviewer asked him if the special characters like $, @, |, ^, ~ have any usage in c

Answer 1

@ is generally invalid in C; it is not used for anything. It is used for various purposes by Objective-C, but that's a whole other kettle of fish.

$ is invalid as well, but many implementations allow it to appear in identifiers, just like a letter. (In these implementations, for instance, you could name a variable or function $$$ if you liked.) Even there, though, it doesn't have any special meaning.