evert@localhost ~/C++/allegro $ g++ units.cpp main.cpp `allegro-config --cflags --static` -o risk
units.cpp:15:2: warning: no newline at end of file
/tmp/ccNpWBRs.o:(.bss+0x0): multiple definition of `my_datafile'
/tmp/ccnOrmMi.o:(.bss+0x0): first defined here
/tmp/ccnOrmMi.o: In function `unit::is_selected()':
units.cpp:(.text+0x1f): undefined reference to `buffer'
/tmp/ccNpWBRs.o: In function `main':
main.cpp:(.text+0x1b4): undefined reference to `buffer'
main.cpp:(.text+0x281): undefined reference to `buffer'
main.cpp:(.text+0x29d): undefined reference to `buffer'
main.cpp:(.text+0x2dc): undefined reference to `buffer'
/tmp/ccNpWBRs.o:main.cpp:(.text+0x320): more undefined references to `buffer' follow
collect2: ld returned 1 exit status
evert@localhost ~/C++/allegro $