Thanks. GPIO.cpp was not in the project, so I couldn't remove it. However, Plugins->Find broken files in project succeeded in removing both GPIO.cpp and GPIO.o from the project. How do I find files in the project that have no .cpp files?
I am also getting placed on the link command the library "/home/pi/rpi-rgb-led-matrix/lib/librgbmatrix.a", but I can't find any reference in either the Project->Build options or in the Project->Properties. Does Code::blocks hide this somewhere?
On the build, I am now getting:
-------------- Build: Debug in linktest (compiler: GNU GCC Compiler)---------------
g++ -L/home/pi/linktest/ -L/home/pi/linktest/ -L/home/pi/rpi-rgb-led-matrix/lib -o bin/Debug/linktest obj/Debug/ButtonSetup.o obj/Debug/main.o obj/Debug/SrjGPIO.o -pthread -pthread /home/pi/linktest/obj/Debug /home/pi/rpi-rgb-led-matrix/lib/librgbmatrix.a
/usr/bin/ld: cannot find /home/pi/linktest/obj/Debug: File format not recognized
collect2: error: ld returned 1 exit status
Process terminated with status 1 (0 minute(s), 0 second(s))
2 error(s), 0 warning(s) (0 minute(s), 0 second(s))
I have gotten this before, and I am not sure why. Could someone please enlighten me on why I am getting "File format not recognized."