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.

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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Originally Posted by ahn1162

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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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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You might have to write a thunk using some assembly language.

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Or just give the correct function type like __cdecl, __stdcall, __fastcall, and others
http://msdn2.microsoft.com/en-us/lib...fy(VS.71).aspx

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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Originally Posted by vart

Or just give the correct function type like __cdecl, __stdcall, __fastcall, and others

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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.