Question

I have a bunch of files in different folders:

/ai/client.cpp   # contains the main function

/ai/utils/geometry.h   
/ai/utils/geometry.cpp

/ai/world/world.h
/ai/world/world.cpp
/ai/world/ball.h
/ai/world/ball.cpp
/ai/world/bat.h
/ai/world/bat.cpp

How do I write a makefile to compile this program? I’m using Ubuntu.

Answer 1

Make is a versatile tool, and there are many different subtleties to using it. However, you can keep things simple:

OBJ := ai/utils/geometry.o ai/world/world.o ai/world/ball.o ai/world/bat.o

all: ai/client
.PHONY: all  # specific to GNU make, which is what Ubuntu provides

ai/client: ai/client.o $OBJ

# this rule means each .cpp file depends on its corresponding header
# and, since the .o files depend on .cpp files (a builtin make rule),
# they will be recompiled if the headers change
#
# you can also get more complex and generate dependencies automatically
# look at the -MM option for gcc, for example
%.cpp: %.h