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

To complete the other answers. The C99-Standard in 5.2.1.3:

Both the basic source and basic execution character sets shall have the following members:

the 26 uppercase letters of the Latin alphabet

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

the 26 lowercase letters of the Latin alphabet

a b c d e f g h i j k l m n o p q r s t u v w x y z

the 10 decimal digits

0 1 2 3 4 5 6 7 8 9

the following 29 graphic characters

! " # % & ' ( ) * + , - . / : ; < = > ? [ \ ] ^ _ { | } ~

All other characters maybe not even exist. (And should not be used)

But there is also this point in the Common extensions: Annex J, J.5.2:

Characters other than the underscore _, letters, and digits, that are not part of the basic source character set (such as the dollar sign $, or characters in national character sets) may appear in an identifier (6.4.2).

Which is basically what duskwuff already wrote.