extern storage class — External storage class specifier
storage-class-specifier := extern linkage-specification ::= extern string-literal { [declaration-seq] } | extern string-literal declaration
The extern
storage class
specifier marks a declaration as having external linkage. An external
object or function can be defined in one file and used in other
files.
The extern
keyword can also
be used to specify language linkage: you provide the language name as
a string literal. The "C++
"
language is the default. "C
"
linkage is also supported. Other languages are
implementation-defined.