How to call external functions without a .DLL (just using a .H and .LIB file)?

Hello everyone,
actually I'm facing little difficulties on how to get an external function getting called from within CVI (Version 2009).
I was supplied with a .H file and a .LIB file to call an external function from within my CVI project. The .H file looks like this:
void exportedFunction(double *parameter);
As far as I know, the external function was written with MS Visual C++ 6.
So I tried to statically link to the extern al function like this:
- Add the .H file and the .LIB file to the CVI project
- #include the .H file where I needed to call the external function
- do the external function call
When building I get an unresolved external function call error from CVI so this seems not to be working.
I made some searches around and got up with two possible issues. Maybe one of you can help me get a bit further and get things working.
1) The "real" function code is located in the DLL file which was not delivered to me. Or is there a way to get things done (call external functions) just with a .H and a .LIB file (without any .DLL file included)?
2) The external function does not export according to "C-Style" rules. The function signature in the .H file shows no things like
extern "C" __declspec(dllexport) void __stdcall ...
Or maybe it's a combination of both issues (missing .DLL + wrong export style of function)?
I guess I could get around the wrong export style of the function when I manage to write a wrapper around the original function that actually uses C-Style exporting. But I guess I need the .DLL file for this try as well.
Thank you for your answers.
Best regards,
Bernd
Solved!
Go to Solution.

There is no need for the dllexport stuff. There is also the option for a static library without any DLL. But the 'extern "C"' is essential, because it forces the C++ compiler, which was probably used to compile the library , to use C calling convention.
If you can't ask the provider of the library to provide a version which was compiled using C calling convention the way to go is to write a wrapper with VC++6 around that library which reexports the functions using C calling convertion. Something like
extern "C" type0 myfunc1(type1 arg1, ...) {
return func1( arg1,...);
for every function , you need to use.
BTW. "unresolved symbol" is the linker error message, you can expect if you try to link C code against a library build with C++ calling convention.

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