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[hillbilly78]

Hi everyone,
I am trying to create a Fortran dll using the Plato IDE that can be used in my Visual Basic programs. I would like to know the procedures required to

1.) Make a dll using Plato (including settings required, etc)
2.) Implement the dll in Visual Basic (including declarations and references, etc)

Also has any one got any websites or information they could share regarding how data is passed between the dll and Visual Basic (e.g. what data types can be used) and if there are any pitfalls, etc.

Thanks in advance.

Stuart

[PaulLaidler]

Stuart

The place to start is "Calling an FTN95 DLL from Visual Basic" in the FTN95 help file.

You need to create a "Fortran Application Extension" project in Plato3.

You can pass simple scalars and arrays (by reference) but avoid passing strings.

Try to avoid using global data in the DLL otherwise things get more difficult (you will need to use LoadLibrary and possibly your own "DLLMain")

Use F_STDCALL in your subprogram definition.

[hillbilly78]

I have created a Fortran Application Extension project with just one function in which is:

F_STDCALL INTEGER*4 FUNCTION MyFunc(X)
INTEGER*4 X
MyFunc=X
END

I have created the DLL called "FortranTestDLL.dll" (ticking the export all option under Project->Properties->Linker Options) and then placed it in my Visual Basic project directory. In my Visual Basic Project I declared the function in the DLL using:

Public Declare Function MyFunc Lib "FortranTestDLL.dll" (ByRef X As Long) As Long

When the VB project is executed an error occurs which is

"Run-time error '453':

Can't find DLL entry point MyFunc in FortranTestDLL.dll"

Is there something else I am missing?

Thanks,
Stuart

[PaulLaidler]

Fortran exports are uppercase MYFUNC.

[hillbilly78]

That works fine now, thanks.

Stuart