How to add existing library containing .h and .cpp in same folder

[devararendy]

Hi I would like to ask. How to add existing library containing .h and .cpp in same folder ?
Because in default, the .h and .cpp is located in different folder. .h is inside include folder and the .cpp is inside src folder.

But I have a library (MAVlink library) which is containing .h and .cpp in same folder. Also there are some subfolder inside the library folder (inside MAVlink library).

I've tried putting the MAVlink library inside include folder, but when i build it, i got error undefined reference ....

and I could not see any problem in "Problems Tab"

Hopefully You guys can help.
Thank You so much for your time for helping me

Best regards

Rendy