Makefile: How to correctly include header file and its directory?
The preprocessor is looking for StdCUtil/split.h
in
./
(i.e./root/Core/
, the directory that contains the #include statement). So./
+StdCUtil/split.h
=./StdCUtil/split.h
and the file is missing
and in
$INC_DIR
(i.e.../StdCUtil/
=/root/Core/../StdCUtil/
=/root/StdCUtil/
). So../StdCUtil/
+StdCUtil/split.h
=../StdCUtil/StdCUtil/split.h
and the file is missing
You can fix the error changing the $INC_DIR
variable (best solution):
$INC_DIR = ../
or the include directive:
#include "split.h"
but in this way you lost the "path syntax" that makes it very clear what namespace or module the header file belongs to.
Reference:
- C++ #include semantics
EDIT/UPDATE
It should also be
CXX = g++
CXXFLAGS = -c -Wall -I$(INC_DIR)
...
%.o: %.cpp $(DEPS)
$(CXX) -o $@ $< $(CXXFLAGS)
These lines in your makefile,
INC_DIR = ../StdCUtil
CFLAGS=-c -Wall -I$(INC_DIR)
DEPS = split.h
and this line in your .cpp file,
#include "StdCUtil/split.h"
are in conflict.
With your makefile in your source directory and with that -I
option you should be using #include "split.h"
in your source file, and your dependency should be ../StdCUtil/split.h
.
Another option:
INC_DIR = ../StdCUtil
CFLAGS=-c -Wall -I$(INC_DIR)/.. # Ugly!
DEPS = $(INC_DIR)/split.h
With this your #include
directive would remain as #include "StdCUtil/split.h"
.
Yet another option is to place your makefile in the parent directory:
root
|____Makefile
|
|___Core
| |____DBC.cpp
| |____Lock.cpp
| |____Trace.cpp
|
|___StdCUtil
|___split.h
With this layout it is common to put the object files (and possibly the executable) in a subdirectory that is parallel to your Core
and StdCUtil
directories. Object
, for example. With this, your makefile becomes:
INC_DIR = StdCUtil
SRC_DIR = Core
OBJ_DIR = Object
CFLAGS = -c -Wall -I.
SRCS = $(SRC_DIR)/Lock.cpp $(SRC_DIR)/DBC.cpp $(SRC_DIR)/Trace.cpp
OBJS = $(OBJ_DIR)/Lock.o $(OBJ_DIR)/DBC.o $(OBJ_DIR)/Trace.o
# Note: The above will soon get unwieldy.
# The wildcard and patsubt commands will come to your rescue.
DEPS = $(INC_DIR)/split.h
# Note: The above will soon get unwieldy.
# You will soon want to use an automatic dependency generator.
all: $(OBJS)
$(OBJ_DIR)/%.o: $(SRC_DIR)/%.cpp
$(CC) $(CFLAGS) -c $< -o $@
$(OBJ_DIR)/Trace.o: $(DEPS)