Question

My makefile works alright (GNU Make), but I was wondering whether

• There is a way to make a new directory “bin” and put all the .o in there
• If the answer to “1” is “yes”, can the instruction “make clean” delete the folder “bin”?
• Avoid having to write all the .cpp and .o filenames?

CFLAGS = -Wall -g
CC = g++
EXEC = main
OBJ = listpath.o Parser.o main.o

all: $(EXEC)

listpath.o: src/listpath.cpp
  $(CC) $(CFLAGS) -c src/listpath.cpp

Parser.o: src/Parser.cpp 
  $(CC) $(CFLAGS) -c src/Parser.cpp

main.o: src/main.cpp
  $(CC) $(CFLAGS) -c src/main.cpp

$(EXEC): $(OBJ)
  $(CC) $(CFLAGS) $(OBJ) -o $(EXEC)

.cpp.o:
  $(CFLAGS) $<

.PHONY: clean
clean:
  rm $(OBJ) $(EXEC)

Answer 1

Starting with the last question, you can define implicit rules to convert .c files to .o files.

bin/%.o : src/%.cpp | bin
  $(CC) $(CFLAGS) -c $< -o $@

This will also out the .o files to the bin/ directory.

Now your result rule will look like:

$(EXEC): $(addprefix bin/, $(OBJ))
  $(CC) $(CFLAGS) $^ -o $@

To clean the bin/ directory, simple change your clean rule to:

clean:
  rm -rf bin/ $(EXEC)

Finally, add a rule to create the bin directory:

bin:
  mkdir -p bin