EXTERN


Declares a variable, array or object having external linkage

Syntax:
Extern [ Import ] symbolname[ (subscripts) ] [ Alias "aliasname" ] as DataType [, ...]

Parameters:
symbolname
The name of the variable, array or object.
aliasname
An alternate external name for the variable, array or object.

Description:
Declares symbolname as an external name, meaning it is global to external modules. Extern only declares variables, arrays and objects, and does not define them (different from Common or Dim). It also has the effect of making symbolname a shared name, meaning it is visible within procedures (see Shared). A symbolname declared as external name can be (re)defined (using Dim or Redim) only in a single external module.

If Alias is used, aliasname will be used as the external name rather than symbolname, and its case will be preserved.

If Import is used, the name will be added to the dynamic library import list so its address can be fixed at run-time.

Examples:
'' extern1.bas

Extern Foo Alias "foo" As Integer

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


Dialect Differences:
Differences from QB:
See also:
Back to Modularizing
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