Using modules with global variables along with external routines in DLLs

[millerdl]

Hi all,

I am having some problems with using global variables with external routines using DLLs. I compile something like this into a DLL:

MODULE my_mod

IMPLICIT NONE

INTEGER, SAVE :: key

EXTERNAL test

CONTAINS

SUBROUTINE call_test(key)

call test(1)

END SUBROUTINE call_test

END MODULE my_mod

SUBROUTINE test(i)

USE my_mod

IMPLICIT NONE

INTEGER :: i

PRINT*,"i=",i

PRINT*,"key=",key

END SUBROUTINE test

I then call the subroutine call_test() from, say, R with the key value as 2 I get the following output:

i=1

key=0

Apologies if I am missing something very obvious I am a Fortran 77 programmer attempting to learn F90/95.

Thanks in advance!

[thomas_boehme · Accepted solution]

In your subroutine call_test you are declaring key as an argument. Therefore, key will be a local variable to the subroutine and not the module variable.

Modify your code like that and it should work:

SUBROUTINE call_test(keyval)

key = keyval

call test(1)

END SUBROUTINE call_test

regards,
Thomas

[millerdl]

Thanks Thomas, that's solved my problem! I can't believe I didn't think of doing that!

Quoting - thomas_boehme

In your subroutine call_test you are declaring key as an argument. Therefore, key will be a local variable to the subroutine and not the module variable.

Modify your code like that and it should work:

SUBROUTINE call_test(keyval)

key = keyval

call test(1)

END SUBROUTINE call_test

regards,
Thomas