Libusb undefined reference to

you have to set the library linker flag for compilation in the linker, you can get a full list in the console by executing

pkg-config --list-all

These are the libraries which you have installed on your system and you have to link against the ones you want to use. so in your example it is libusb so you do

pkg-config --libs libusb

there should be the output

-lusb

or

-lusb-1.0

This gives you the flag you have to pass to the linker. e.g.

g++ myfile.cpp -lusb[-1.0]

Then you edit the configuration of the project and search for the linkerflags, there should be a textfield for that somewhere in the buildoptions. i'm not quite shure where to find it but googling for it suggested:

Project -> Properties -> C/C++
Build -> Miscellaneous -> flags

After you found it, just add the linker flag in the textfield and you should be fine.

EDIT

since my answer is the accepted one, I also added the other flag that seems to work for a lot of people.

What is your linker command line? You need to have -lusb in the linking command; just having the header included won't work.

I did face the same problem. But I was able to solve it by adding '-lusb-1.0' to the linker.

e.g : g++ myfile.cpp -lusb-1.0