Makefile issue: smart way to scan directory tree for .c files

Question

I am doing a project which is growing pretty fast and keeping the object files up date is no option. The problem beyond wildcard command lies somewhere between \"I do not wa

Answer 1

I like to do the following.

Create Variables to Each Directory of the Project

SRCDIR = src                                                           
OBJDIR = obj
LIBDIR = lib
DOCDIR = doc
HDRDIR = include

CFLAGS = -g -Wall -O3

Get Only the Internal Structure of SRCDIR Recursively

STRUCTURE := $(shell find $(SRCDIR) -type d)     

Get All Files inside the STRUCTURE Variable

CODEFILES := $(addsuffix /*,$(STRUCTURE))
CODEFILES := $(wildcard $(CODEFILES))            

Filter Out Only Specific Files

# Filter Only Specific Files                                
SRCFILES := $(filter %.c,$(CODEFILES))
HDRFILES := $(filter %.h,$(CODEFILES))
OBJFILES := $(subst $(SRCDIR),$(OBJDIR),$(SRCFILES:%.c=%.o))

# Filter Out Function main for Libraries
LIBDEPS := $(filter-out $(OBJDIR)/main.o,$(OBJFILES))

Now it is Time to create the Rules

compile: $(OBJFILES)

$(OBJDIR)/%.o: $(addprefix $(SRCDIR)/,%.c %.h)
    $(CC) -c $< -o $@ $(CFLAGS) 

With this approach, you can see that I'm using the STRUCTURE variable only to get the files inside the SRCDIR directory, but it can be used for others purposes as well, like mirror the SRCDIR inside OBJDIR once STRUCTURE stores only the internal sub-directories. It is quite useful after clean operations like:

clean:
    -rm -r $(OBJDIR)/*

NOTE: The compile rule only works well if for each *.c there is the corresponding *.h file (with the same base name, I mean).