Add the other source file to the project!
Build -> Rebuild gives me this as the full rebuild log.
-------------- Clean: Debug in exercise (compiler: GNU GCC Compiler)---------------
Cleaned "exercise - Debug"
-------------- Build: Debug in exercise (compiler: GNU GCC Compiler)---------------
i686-w64-mingw32-g++.exe -Wall -fexceptions -g -c C:\Users\stahta01\devel\open_source_code\no_version_control\Test\exercise\add.cpp -o obj\Debug\add.o
i686-w64-mingw32-g++.exe -Wall -fexceptions -g -c C:\Users\stahta01\devel\open_source_code\no_version_control\Test\exercise\main.cpp -o obj\Debug\main.o
i686-w64-mingw32-g++.exe -o bin\Debug\exercise.exe obj\Debug\add.o obj\Debug\main.o
Output file is bin\Debug\exercise.exe with size 1.69 MB
Process terminated with status 0 (0 minute(s), 14 second(s))
0 error(s), 0 warning(s) (0 minute(s), 14 second(s))
Tim S.