Using the GNU C++ command, in the root directory:
g++ -std=c++17 tictactoe.cpp board/board.cpp game/game.cpp -o tictactoe;
Note: the c++17 flag is important, as some vector initializations are only valid in C++11+
The above command will compile and link all object files into an executable file called tictactoe.
Run the executable from a terminal using ./tictactoe.
This was built without OOP. Specifically built using procedural and functional programming.
The game and board object files contain only functions to build and process the 2D vector board and user input.
The primary program lives in tictactoe.cpp, keeping things slim and modular.