When you create a Fortran procedure that references a C procedure you declare the C procedure name with the DLL_IMPORT attribute in your Fortran code. The procedure may be a subroutine or function. C functions may only return the Fortran equivalent of default INTEGER, REAL, or LOGICAL results.
program main implicit none real, dll_import :: My_Dll_Routine ! case-sensitive real :: x x = My_Dll_Routine() write (*,*) x end program main
Before building the Fortran main program with LF95, you must have a DLL and import library available. Refer to your C manual for specifics on creating a DLL. If the C compiler does not create a compatible import library (.LIB file) for the DLL, proceed as described above, see Building Import Libraries.
If the DLL was created with Microsoft Visual C++, use the -ml msvc option:LF95 source.f90 -win -ml msvc dll_src.lib
If the DLL was created with Borland C++, use the -ml bc option:LF95 source.f90 -win -ml bc dll_src.lib
Where dll_src.lib is the name of the Microsoft compatible import library.
There are examples of calling C DLLs in the