Static Storage-Class Specifiers

The static storage-class specifiers, static and extern, can be applied to objects and functions. The following table shows where the keywords static and extern can and cannot be used.

Use of static and extern

Construct

Can static

be Used?

Can extern

be Used?

Function declarations within a block

No

Yes

Formal arguments to a function

No

No

Objects in a block

Yes

Yes

Objects outside a block

Yes

Yes

Functions

Yes

Yes

Class member functions

Yes

No

Class member data

Yes

No

typedef names

No

No

A name specified using the static keyword has internal linkage except for the static members of a class that have external linkage. That is, it is not visible outside the current translation unit. A name specified using the extern keyword has external linkage unless previously defined as having internal linkage. For more information about the visibility of names, see Scope and Program and Linkage.

NoteNote

Functions that are declared as inline and that are not class member functions are given the same linkage characteristics as functions declared as static.

A class name whose declaration has not yet been encountered by the compiler can be used in an extern declaration. The name introduced with such a declaration cannot be used until the class declaration has been encountered.

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