What does C++ language definition say about the extent of the static keyword?

Question

In C++, if I have a class:

class Example {
  static int s_One, s_Two;

  ...
};

Does the language clearly define that s_Two is also static?

In other words, does the static keyword extent go everywhere the int goes, or can it be like * and only apply to one variable?

This question can be answered by reading [the standard](http://eel.is/c++draft/). But, why don't you simply remove the ambiguity by declaring each variable on its own? — Jesper Juhl, Aug 05 '19 at 16:43
@JesperJuhl: Arguably, most answers about C++ can be answered by reading the standard. But the standard is big and sometimes difficult to navigate. — rodrigo, Aug 05 '19 at 16:46
@JesperJuhl The answer might also be valuable to other people. — ruohola, Aug 05 '19 at 17:19
it would be pretty stupid to not apply all the declarators to all the variables introduced by the declaration... "C++: hold my beer `int* a, b`" — bolov, Aug 11 '19 at 22:41

score 20 · Accepted Answer · answered Aug 05 '19 at 16:50

20

Yes, it applies to every name in that declaration:

[dcl.stc]/1: [..] At most one storage-class-specifier shall appear in a given decl-specifier-seq [..] The storage-class-specifier applies to the name declared by each init-declarator in the list [..]

answered Aug 05 '19 at 16:50

Lightness Races in Orbit

378,754
76
643
1,055

Vlad from Moscow · Answer 2 · 2019-08-05T16:59:09.000

2

According to the C++ 17 Standard (10 Declarations)

2 A simple-declaration or nodeclspec-function-declaration of the form

attribute-specifier-seqopt decl-specifier-seqopt init-declarator-listopt ;

And (10.1 Specifiers):

1 The specifiers that can be used in a declaration are

decl-specifier:
    storage-class-specifier
    ...

So in this declaration

static int s_One, s_Two;

the decl-specifier-seq contains two decl-specifiers, static (storage class specifier) and int. Thus the storage class specifier static describes the both variables in the init-declarator-list s_One and s_Two.

edited Aug 05 '19 at 16:59

answered Aug 05 '19 at 16:45

Vlad from Moscow

301,070
26
186
335

1

That's not enough; this doesn't show that the SCS applies to both, just that is possible. – Rakete1111 Aug 05 '19 at 16:46
1

I'd still write `static int s_One; static int s_Two;`. Much more readable and unambiguous. – Jesper Juhl Aug 05 '19 at 16:47
@JesperJuhl No, this is invalid C++ syntax. – Vlad from Moscow Aug 05 '19 at 16:48
3

No, it is not. Why do you say it is invalid? – Doch88 Aug 05 '19 at 16:51
2

@VladfromMoscow why? – Henri Aug 05 '19 at 16:51
3

@VladfromMoscow How is declaring two separate `static` `int`s invalid syntax? – Jesper Juhl Aug 05 '19 at 16:51
1

@Doch88 I did not see that there is a semicolon instead of comma.:) – Vlad from Moscow Aug 05 '19 at 16:52
1

@Rakete1111 What is not enough for you? – Vlad from Moscow Aug 05 '19 at 16:59

What does C++ language definition say about the extent of the static keyword?

2 Answers2