Can I compile all .cpp files in src/ to .o's in obj/, then link to binary in ./?

build-process, c++, makefile

Solution

Makefile part of the question

This is pretty easy, unless you don't need to generalize try something like the code below (but replace space indentation with tabs near g++)

SRC_DIR := .../src
OBJ_DIR := .../obj
SRC_FILES := $(wildcard $(SRC_DIR)/*.cpp)
OBJ_FILES := $(patsubst $(SRC_DIR)/%.cpp,$(OBJ_DIR)/%.o,$(SRC_FILES))
LDFLAGS := ...
CPPFLAGS := ...
CXXFLAGS := ...

main.exe: $(OBJ_FILES)
   g++ $(LDFLAGS) -o $@ $^

$(OBJ_DIR)/%.o: $(SRC_DIR)/%.cpp
   g++ $(CPPFLAGS) $(CXXFLAGS) -c -o $@ $<

Automatic dependency graph generation

A "must" feature for most make systems. With GCC in can be done in a single pass as a side effect of the compilation by adding `-MMD` flag to `CXXFLAGS` and ` -include $(OBJ_FILES:.o=.d) ` to the end of the makefile body:

CXXFLAGS += -MMD
-include $(OBJ_FILES:.o=.d)

And as guys mentioned already, always have GNU Make Manual around, it is very helpful.

Problem

My project directory looks like this: ``` /project Makefile main /src main.cpp foo.cpp foo.h bar.cpp bar.h /obj main.o foo.o bar.o ``` What I would like my makefile to do would be to compile all `.cpp` files in the `/src` folder to `.o` files in the `/obj` folder, then link all the `.o` files in `/obj` into the output binary in the top-level folder `/project`. I have next to no experience with Makefiles, and am not really sure what to search for to accomplish this. Also, is this a "good" way to do this, or is there a more standard approach to what I'm trying to do?

Original source