Problems when use JSBSim in C++

[DreamerSurpass]

I want to write script in C++ to run JSBSim, just like Reference Manual.

But compiler cannot find FGFDMExec.h thought I have added the scr path.

I'm afraid I'm not familiar with C++. Any ideas? Thanks a lot.

[bcoconni]

I'd say your best course of action is to use the MSVC project files that are included with JSBSim. Open JSBSim.sln with Microsoft Visual Studio and compile the project. You should get an executable JSBSim.exe. From that point on, you could hack the file src/JSBSim.cpp to your liking and recompile the executable using MSVC.

[DreamerSurpass]

Thanks for your reply. I have used MSVC to build JSBSim, and I tested JSBSim.exe, it runs correctly. Now I want to build JSBSim.lib, and link it in my own code. I build a new Project and add src path and JSBSim.lib, then I run JSBSim_minimal.cpp, but when I instantiate FGFDMExec, there is a bug called "LNK2019 unsolved external symbol _declspec(dllimport)", how can I deal with this?

[DreamerSurpass]

I found if I annotating the code in JSBSim_API.h, and use JSBSim.lib in my own main.cpp, this error will not exist.

Original: Add JSBSim.lib and run:

After annotate the code in JSBSim_API.h, I can run my own project correctly:

Any Ideas?

[seanmcleod]

The JSBSIM_API attributes are designed to be used when JSBSim is being built or used as a DLL. When the DLL is being built then JSBSIM_EXPORT will be defined which ensures that all the C++ classes are exported by the DLL. If a client app is using the JSBSim DLL then JSBSIM_EXPORT won't be defined which means JSBSIM_API will be expanded to __declspec(dllimport) basically telling the linker about the C++ classes in the DLL.

Now in your case if you've built JSBSim as a static lib and then you're trying to link to it as a static lib rather than use the DLL version then you must ensure that JSBSIM_STATIC_LINK is defined in your project, i.e. no need to go and comment things out in JSBSim_API.h, since in this case look at the #else section where JSBSIM_API is defined as nothing.

[DreamerSurpass]

Yes, I'm trying to link to it as a static lib rather than use DLL version, but I don't quite understand how to define JSBSIM_STATIC_LINK in my project. Does this mean add Additional Dependencies in properties like this?

Or does this mean directly add define JSBSIM_STATIC_LINK in main.cpp code? Could you please give me a more specific explanation or a demo code demonstration? Thank you for your patient answer!

[seanmcleod]

No Additional Dependencies for the Linker are additional libraries, both regular static libs and import libs for DLLs that you want to link against.

The #defines in the code are processed by the pre-processor, before the compiler starts parsing the source code.

I'm afraid I'm not familiar with C++.

That's going to be tricky, since C++ isn't the easiest programming environment to get familiar with. You'll probably want to find some online tutorials/lessons that give you at least some of the basics.

[DreamerSurpass]

Thank you again for your patience.

That's going to be tricky, since C++ isn't the easiest programming environment to get familiar with. You'll probably want to find some online tutorials/lessons that give you at least some of the basics.

And thanks for your advice, I'll continue to learn.