evert@localhost ~/C++/allegro $ g++ units.cpp main.cpp `allegro-config --cflags --static` -o risk
units.cpp:16:2: warning: no newline at end of file
units.h:4: error: redefinition of 'class unit'
units.h:5: error: previous definition of 'class unit'
units.h:20: error: redefinition of 'unit::unit()'
units.h:20: error: 'unit::unit()' previously defined here
evert@localhost ~/C++/allegro $