c++classgrammaridentifier

Class with no name

I read this about class in the C++ standard document:

A class is a type. Its name becomes a class-name (9.1) within its scope.

class-name: identifier template-id

I found this grammar for an identifier in the C++ Standard:

 2.10 Identifiers
 identifier: nondigit
 identifier nondigit
 identifier digit

 nondigit: one of universal-character-name 
 _ 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 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 
 digit: one of 0 1 2 3 4 5 6 7 8 9

Now I tried doing this:

class
{
public:
  int i;
};

and it compiles fine without any name.

Can anyone give me an explanation regarding this? Isn't it a violation of the grammar specified for an identifier?

Nawaz had asked a follow up question regarding the standard compliance of the code I had given. Those interested can check it out here.

Solution

  • The grammar goes

    class-specifier:
    class-head { member-specification_opt }

class-head:
    class-key attribute-specifier-seq_opt class-head-name class-virt-specifier-seq_opt base-clause_opt
    class-key attribute-specifier-seq_opt base-clause_opt

class-key:
    class
    struct
    union

    In your case, the second production of class-head is used -- no class-name is involved.