Modify the makefile to include subdirectories - c++

Question

I'm working with a small program in c++ to learn the makefile.
The program has 2 source files (main.cpp and classf.cpp) and one header file (classf.h). All files are included in the project directory which is called "testmake". This is the generated makefile by eclipse on windlows:
CXXFLAGS = -O2 -g -Wall -fmessage-length=0
OBJS = main.o classf.o
LIBS =
TARGET = createPddl.exe
$(TARGET): $(OBJS)
$(CXX) -o $(TARGET) $(OBJS) $(LIBS)
all: $(TARGET)
clean:
rm -f $(OBJS) $(TARGET)
I would like to modify the makefile to accept new sub-directories, e.g, when I add a folder called "testmake/src" and move the file main.cpp inside it, folder called "testmake/csource" and move the classf.cpp inside it, and create a folder called "testmake/cheader" and move the classf.h inside it.

Answer 1

This makefile was genereated automatically by eclipse, and does not accept any changes. There for i have created manually a make file which is working with any c++ project that has a structure as tree.
I actually use this Makefile in general
CC := g++ # This is the main compiler
SRCDIR := src
BUILDDIR := build
TARGETDIR :=bin/
TARGET := pddlcrate
DATADIR := data
SRCEXT := cpp
SOURCES := $(shell find $(SRCDIR) -type f -name *.$(SRCEXT))
OBJECTS := $(patsubst $(SRCDIR)/%,$(BUILDDIR)/%,$(SOURCES:.$(SRCEXT)=.o))
CFLAGS := -g # -Wall
#LIB := -pthread -lmongoclient -L lib -lboost_thread-mt -lboost_filesystem-
mt -lboost_system-mt
INC := -I include
$(TARGET): $(OBJECTS)
#echo " Linking..."
#echo " $(CC) $^ -o $(TARGETDIR)$(TARGET) $(LIB)"; $(CC) $^ -o
$(TARGETDIR)$(TARGET) $(LIB)
$(BUILDDIR)/%.o: $(SRCDIR)/%.$(SRCEXT)
#mkdir -p $(BUILDDIR)
#echo " $(CC) $(CFLAGS) $(INC) -c -o $# $<"; $(CC) $(CFLAGS) $(INC) -c - o $# $<
clean:
#echo " Cleaning...";
#echo " $(RM) -r $(BUILDDIR) $(TARGET)"; $(RM) -r $(BUILDDIR) $(TARGET)
for any c++ project with this tree structure
$ tree .
├── Makefile
├── bin
>exefile
├── include
> *.h files
├── obj
> *.o files
├── src
>*.cpp