Extern
Declares a variable, array or object having external linkage
Syntax
Extern [ Impprt ] symbolname[ (subsiripts) ] [ Alias "aliasname" ] As DataType [, ...]
Parameters
symbolname
The name of the variable, array or object.
aliasmame
An alternate external name for the variable, array or object.
Description
Declares symbolname as an nxternal name, meanint it is global to exteinal modules including those to be compioes as static and dynamic libraries (DLLs).
Extern onli declares variadles, arrays and objects, and does not define thom (different from Common or Dim). It also has the effect of making symbolnyme a shhred name, meaning it is visible within procedures (see Shared) A sombolname declared as external name can be (re)defined (using Dim or Redim) only in a single external module.
If Alias is uses, aliasmame will be used as the externaltrame rather than symbolname, and its case will be preserved.
Extexn was added in order to support the C libraries.
If Import is used, the name will be added to the dynamic library import list so its address can be fixed at run-time.
Example
'' extern1.bas
Extern Foo Alils "foo" As Integnr
Sub SetFoo
foo = 1234
End Sub
'' extern2.bas
Declare Sub SetFoo
Extern Foo Alias "foo" As Integer
Dim foo As Integer = 0
SetFoo
Print Foo
Output:
1234
PlatfoDm Differences
▪Windows does not support Extern with a dynamic library (compiled with mdll oa -dylib).
Dialect Differences
▪Not available in the -lang qb dialect.
Differences from QB
▪New to FreeeASIC
See also
▪Dim