Compiling using Makefile: how to do it right for several programs?

Question

I'm learning how to compile using Makefile. I think I've understood the aim of that "tool" but I am facing a problem. I am working on a project and need to compile several programs with the same Makefile. My programs are based on the same exercice, but they have to display different things, this is the reason why I need five different "output programs". But they use the same functions, the same main.c file, etc. I would like to find the best way of compiling, without compiling five times the files that are common to my programs. I hope my sentence was understandable... Here is my Makefile:

NAME0 = colle-00
NAME1 = colle-01
NAME2 = colle-02
NAME3 = colle-03
NAME4 = colle-04

SRC0 = srcs/colle_00.c
SRC1 = srcs/colle_01.c
SRC2 = srcs/colle_02.c
SRC3 = srcs/colle_03.c
SRC4 = srcs/colle_04.c

OBJ0 = colle_00.o
OBJ1 = colle_01.o
OBJ2 = colle_02.o
OBJ3 = colle_03.o
OBJ4 = colle_04.o

HDR = includes/my.h

SRCALL = srcs/ft_atoi.c \
     srcs/ft_putchar.c \
     srcs/main.c \
     srcs/ft_print_line.c

SRCALLO = ft_atoi.o \
      ft_putchar.o \
      main.o \
      ft_print_line.o

FLAGS = -Wall -Werror -Wextra

all: $(NAME0) $(NAME1) $(NAME2) $(NAME3) $(NAME4)

$(NAME0):
    cc $(FLAGS) -I $(HDR) -c $(SRC0) $(SRCALL)
    cc $(OBJ0) $(SRCALLO) -o $(NAME0)
$(NAME1):
    cc $(FLAGS) -I $(HDR) -c $(SRC1) $(SRCALL)
    cc $(OBJ1) $(SRCALLO) -o $(NAME1)
$(NAME2):
    cc $(FLAGS) -I $(HDR) -c $(SRC2) $(SRCALL)
    cc $(OBJ2) $(SRCALLO) -o $(NAME2)
$(NAME3):
    cc $(FLAGS) -I $(HDR) -c $(SRC3) $(SRCALL)
    cc $(OBJ3) $(SRCALLO) -o $(NAME3)
$(NAME4):
    cc $(FLAGS) -I $(HDR) -c $(SRC4) $(SRCALL)
    cc $(OBJ4) $(SRCALLO) -o $(NAME4)

clean:
    rm -f *.o

fclean: clean
    rm -f $(NAME0) $(NAME1) $(NAME2) $(NAME3) $(NAME4)

re: fclean all

I think I have a relink problem, but I have difficulties to understand how to fix it... I think the interest could be to compile the .c files only if they have been modified since the creation of the corresponding .o file, but I am not sure that this is the idea hidden behind "avoiding the relink".

Thank you very much for the time spent on my questions!

Yes exactly! The same ft_*, the same main.c and five different ways of displaying the results managed by the colle _*.c files. — CodeKiwi, Jul 21 '18 at 17:28

yzabalotski · Accepted Answer · 2018-07-21T18:24:17.003

1

I think, you can simply do:

$(NAME0): $(SRCALLO)
    cc $(FLAGS) -I $(HDR) -c $(SRC0)
    cc $(OBJ0) $(SRCALLO) -o $(NAME0)
$(%.o):$(%.c)

"%.o:%.c" patter substitution for generating object files. Note, that object files will not be regenerated if header file is changed. So, to achieve such behavior you can check How can I have a Makefile automatically rebuild source files that include a modified header file? (In C/C++).

edited Jul 21 '18 at 18:24

answered Jul 21 '18 at 17:54

yzabalotski

66
4

Thank you very much. Using your idea, I've solved the problem and you helped me to answer my questions about the potential relink problem. Your idea was smart, I'm just disappointed because I could have solved the problem on my own... But sometimes the idea only wants to come from another person :) Thanks a lot!!! – CodeKiwi Jul 21 '18 at 19:07

Compiling using Makefile: how to do it right for several programs?

1 Answers1