C: compiling with -D in make file - c

Question

Hi i'm having issues while compiling my c program.
I'm using Makefile to compile it.
this is my make file :
# flags per la compilazione
#CFLAGS = -std=c89 -Wpedantic
CC = gcc
SO_HEIGHT= SO_HEIGHT=20
SO_WIDTH= SO_WIDTH=60
LIBS=libs/
OBJ = $(LIBS)ipc_utilities.o $(LIBS)utilities.o $(LIBS)dijkstra.o
OBJMAIN = main.o
OBJSOSOURCES=so_sources.o
OBJTAXI=taxi.o
all : utilities main so_sources taxi clean run
main: $(OBJMAIN) $(OBJ)
$(CC) $(OBJMAIN) $(OBJ)-o main
so_sources: $(OBJSOSOURCES) $(OBJ)
$(CC) $(OBJSOSOURCES) $(OBJ) -o so_sources
taxi: $(OBJTAXI) $(OBJ)
$(CC) $(OBJTAXI) $(OBJ)-o taxi
utilities:
$(CC) -c -D $(SO_HEIGHT) -D $(SO_WIDTH) -o $(LIBS)utilities.o $(LIBS)utilities.c
clean:
rm -f *.o
rm -f $(LIBS)*.o
clear
# il target run si usa talvolta per eseguire l'applicazione
run:
./main
this is the error i get :
gcc -c -D SO_HEIGHT=20 -D SO_WIDTH=60 -o libs/utilities.o libs/utilities.c
gcc -c -o libs/ipc_utilities.o libs/ipc_utilities.c
In file included from libs/ipc_utilities.h:4,
from libs/ipc_utilities.c:8:
libs/utilities.h:44:27: error: ‘SO_HEIGHT’ undeclared here (not in a function)
44 | struct strada cityMap[SO_HEIGHT][SO_WIDTH];
| ^~~~~~~~~
libs/utilities.h:44:38: error: ‘SO_WIDTH’ undeclared here (not in a function)
44 | struct strada cityMap[SO_HEIGHT][SO_WIDTH];
| ^~~~~~~~
make: *** [<builtin>: libs/ipc_utilities.o] Error 1
On ipc_utilities.h i include utilities.h :
#include <stdio.h>
#include <stdlib.h>
#include "utilities.h" // error
I'm familiar with makefile , anynone can help?

Answer 1

There are a number of ways to put the pieces together, but since you need both the define name and its value, I would do something like the following:
SO_HEIGHT := 20
SO_WIDTH := 20
CFLAGS := -std=c11 -Wall -Wextra -pedantic -Wshadow
CFLAGS += -DSO_HEIGHT=$(SO_HEIGHT) -DSO_WIDTH=$(SO_WIDTH)
...
$(CCLD) -o $(APPNAME) $(OBJECTS) $(CFLAGS) $(LDFLAGS) $(LIBS)
Now you have the define label and value as part of your CFLAGS variable (e.g. -DSO_HEIGHT=$(SO_HEIGHT)) you do not need to include anything further in your makefile rule.
Of Course, you could also simply do:
SO_HEIGHT := SO_HEIGHT=20
SO_WIDTH := SO_WIDTH=20
CFLAGS := -std=c11 -Wall -Wextra -pedantic -Wshadow
CFLAGS += -D$(SO_HEIGHT) -D$(SO_WIDTH)
It's really however you want to do it.