Setting up 3rd party libraries

[KirkD]

I have a 3rd party library (OpenBabel - www.openbable.org) that was built using VC++ Express 2008 that I'm trying to use in Code::Blocks.  I can link to this library and compile an application through VC++ Express 2008 or through Code::Blocks if I specify VC++ as the compiler of choice.  But, when I switch go the GCC compiler and (to the best of my knowledge) have the libraries specified as well as the correct search paths, I always get "undefined reference to" errors referring to functions within the OpenBabel libraries.

Is it not possible to link to a library built with another compiler?  I could rebuild with GCC, but I would prefer to use these prebuilt libraries.

I appreciate any assistance!

-Kirk

[MortenMacFly]

Is it not possible to link to a library built with another compiler?

It is possible. Notice that you just need to resolve the missing references - that's it. From my experience I can say that usually the import of VC projects into C::B works just fine. Just in a VC project you don't need to explicitly define all required libraries. Visual Studio seems to do some "voodoo" so that in the end the linker is happy. C::B doesn't do such (luckily) so you must make sure that you have setup the project correctly.
So far I had only one (!) VC library that I was not able to use with GCC. Every else worked just fine - even such things like Direct/X.

[KirkD]

Morten,

Thanks for the reply.  I suppose it is at least comforting to know that it is possible.

At this point I've added every library in that I have and pointed to all the appropriate search directories, as far as I know.  Any suggestions on where to look for what I'm missing?  Or is this part of the "voodoo" - finding the missing parts??

-Kirk

[MortenMacFly]

Any suggestions on where to look for what I'm missing?  Or is this part of the "voodoo" - finding the missing parts??

Notice that also the order matters. SO if lib1 requires lib2 you cannot link against lib1 in the first place. Here is what I usually do:

- import VC project
- remove all libs from the project's linker options (only the libs)
- compile
- notice the first missing symbol
- ask google what library this is from -> MSDN helps nicely if it's a MS Windows dependency
- if it's "my" stuff I either know or use the symbol table plugin to find the library that exports the missing symbol.
- like this I add all libs needed step by step and automatically have the right order.

[stahta01]

Is it not possible to link to a library built with another compiler?  I could rebuild with GCC, but I would prefer to use these prebuilt libraries.

If all the exported functions are "C" it is possible. If C++ functions then it is NOT normally possible to change Compilers between client code and library code.

Tim S.

[KirkD]

stahta01  -  Interesting.  I'm not sure of the full nature of the library - not my development - so I don't know for certain about the exports. 

I've gone through the VC++ solution file and found all the listed dependencies for the library that seems to be failing.  Even when included in the "proper" order, etc. I cannot get around the reference failure.

So, I have the choice to rebuild using Code::Blocks or start using VC++ Express.  Code::Blocks is certainly my preference, but it may be more efficacious right now to go the other route.

Thank you both for your input!!

-Kirk

[stahta01]

Compile the Library with the same compiler as the project is the way to go. The Library looks to be C++ to me.

https://sourceforge.net/projects/openbabel/

EDIT: FYI, Code::Blocks is an IDE not an compiler.

Tim S.

[KirkD]

Yes, I realize that Code::Blocks is an IDE - I tend to use Code::Blocks interchangeably with GCC.  oops.  8^)


I'll give the rebuild with GCC a shot.

[PaulS]

If it is C rather than C++ code this link may help -- http://www.emmestech.com/moron_guides/moron1.html.  I was able to use a small Microsoft dll by following the advice.  Even if C++ it may give you a clue about some of the problems.

Can't seem to get that link to format correctly -- may need a moron's guide for that too