Fortran 90 Subroutine in Borland C++ builder

This is a discussion on Fortran 90 Subroutine in Borland C++ builder within the C++ Programming forums, part of the General Programming Boards category; I have a big problem with "Borland C++ Buiolder 6" & FORTRAN90 (Fortan power station 4). I have to use ...

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    Fortran 90 Subroutine in Borland C++ builder

    I have a big problem with "Borland C++ Buiolder 6" & FORTRAN90 (Fortan power station 4). I have to use a FORTRAN 90 subroutine. I use this line in my C++ program:

    extern "C" subroutine_name_(variable);

    but there is a problem in compiling the program. I recive this error massage:

    [Linker Error] Unresolved external 'subroutine_name' referenced from C:\PROJECT\subroutine_name.OBJ

    any help is appreciated.

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    ive never used extern so im just guessing.

    it seems that the function 'subroutine_name(variable)' doesnt exist. are you following a tutorial or something that says to do this? if so i imagine you have to replace 'subroutine_name' with the name of a function and (variable) with whatever the function accepts.

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    Quote Originally Posted by ahn1162 View Post
    I have a big problem with "Borland C++ Buiolder 6" & FORTRAN90 (Fortan power station 4). I have to use a FORTRAN 90 subroutine. I use this line in my C++ program:

    extern "C" subroutine_name_(variable);

    but there is a problem in compiling the program. I recive this error massage:

    [Linker Error] Unresolved external 'subroutine_name' referenced from C:\PROJECT\subroutine_name.OBJ

    any help is appreciated.
    Probably the symbol naming method is different between the C++ compiler and the Fortran compiler. Could be the C++ compiler is inserting a leading underscore and the Fortran compiler is not. It doesn't seem to be a mangling problem because you've properly declared it extern "C".

    But even if you can get it to resolve the symbol, I'm not sure the calling convention is compatible between C++ and Fortran. You might have to write a thunk using some assembly language.

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    CSharpener vart's Avatar
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    You might have to write a thunk using some assembly language.
    Or just give the correct function type like __cdecl, __stdcall, __fastcall, and others
    http://msdn2.microsoft.com/en-us/lib...fy(VS.71).aspx
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    and the hat of wrongness Salem's Avatar
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    You have to read the documentation to see how mixed language programs are built for your compiler. There is nothing standard about the way this is done.
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    Quote Originally Posted by vart View Post
    Or just give the correct function type like __cdecl, __stdcall, __fastcall, and others
    Well, if one of those matches the convention expected by the Fortran compiler, it could work. But the answer won't be found in the Microsoft docs, since this is a third-party Fortran compiler.

    Another thing to watch out for is that arguments in Fortran are passed BY REFERENCE, not by value, which is very different from C and C++. It might be as simply as just declaring all the arguments to be pointers, then again, maybe not.

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