Example makefile for building simple c project recompiling when headers change

Question

Does anyone have a complete makefile that can do the following:

1. Rebuilds the project if a HEADER file changes
2. The cpp files are listed in the makefile

Answer 1

CXX = g++

OBJECTS := main.o C1.o C2.o

all: $(OBJECTS)

%.o : %.cpp
    $(CXX) $(CPPFLAGS) -Wall -MMD -c $< -o $@

-include *.d

EDIT: As TobySpeight points out, this won't work if you build an object file, rename or delete one of the prerequisite source or header files, then try to rebuild the object file; the .d file will still require the missing file, and the build will fail. I neglected to include lines to deal with that case:

%.h: ;
%.cpp: ;

(This is effective, but crude. The more precise approach is to put some sed commands in the %.o rule, so as to add specific null rules to the .d file, one for each prerequisite, but the sed commands are ugly, and the approach above is good enough for almost all cases.)

Answer 2

You can also use CMake for this. Everything you need to write is:

add_executable (exec main.cpp C1.cpp C2.cpp)