Let's say I have several .cpp files which are built by the same way:
main.o : main.cpp
$(CC) -c main.cpp $(COMPILATION_FLAGS)
file1.o : file1.cpp
$(CC) -c file1.cpp $(COMPILATION_FLAGS)
file2.o : file2.cpp
$(CC) -c file2.cpp $(COMPILATION_FLAGS)
How can I write this command only once, and then apply it to main, file1 and file2, to exclude code duplication?
http://www.gnu.org/software/make/manual/html_node/Pattern-Rules.html
http://www.gnu.org/software/make/manual/html_node/Pattern-Examples.html#Pattern-Examples
Something like
%.o : %.cpp
$(CC) -c $(CFLAGS) $(CPPFLAGS) $< -o $#
should do what you want.
Why don't you use CFLAGS and CPPFLAGS rather than COMPILATION_FLAGS?
Related
In this Makefile- I want to copy the $(TGT) binary file after compiled to a sub folder(test) in the same directory. How can I include the copy command of the compiled target file in the Makefile?
CC = g++
CFLAGS = -ansi -std=c++11
LIBS = -L/usr/lib -lstdc++
DEPS = foo.cpp
OBJ = foo.o
TGT+=foo
%.o: %.cc $(DEPS)
$(CC) -c $< $(CFLAGS) -o $#
all: $(TGT)
$(TGT): $(OBJ)
$(CC) $^ $(CFLAGS) $(LIBS) -o $#
# TODO: Need to include the copy command for copying TGT to test folder.
clean:
rm -f *.o $(TGT)
Currently the folder structure is-
<foo>
Makefile
foo.cpp
foo.h
<test>
<..Need "foo" inside this folder>
Is there some reason you can't just change the recipe to copy the file?
Change:
$(TGT): $(OBJ)
$(CC) $^ $(CFLAGS) $(LIBS) -o $#
To:
$(TGT): $(OBJ)
$(CC) $^ $(CFLAGS) $(LIBS) -o $#
cp $# test
You can easily add a rule to copy a file:
all: test/$(TGT)
test/$(TGT): $(TGT)
cp $< $#
suppose CC variable is a compiling command and we don't need any additional flags. Simple part of makefile compiling main.c and next.c to main.o and next.o:
all: main.o next.o
%.o : %.c
$(CC) $< -o $#
Now suppose I would like to have output files in variable:
all: $(OBJ)
OBJ = main.o next.o
%.o : %.c
$(CC) $< -o $#
Of course it won't work. I understand why but I can't find solution. Can you help me?
I wrote this Makefile to move all .o of the project inside a directory 'obj' in the main folder.
Directories
.:
actor/ lib/ Controller.cpp Controller.h Controller.o doc.txt main.cpp main.o Makefile uno VRP*
./actor:
Customer.cpp Customer.h Customer.o Depot.cpp Depot.h Depot.o Route.cpp Route.h Route.o Vehicle.cpp Vehicle.h Vehicle.o
./lib:
Search.cpp Search.h Search.o Utils.cpp Utils.h Utils.o VRP.cpp VRP.h VRP.o
Makefile
CXX=g++
RM=rm -rf
BIN_NAME=VRP
CPPFLAGS=-s -O2 -std=gnu++11 -Wall
SRCS=$(wildcard *.cpp actor/*.cpp lib/*.cpp)
OBJS=$(subst .cpp,.o,$(SRCS))
all: $(OBJS_DIR) $(BIN_NAME)
$(OBJS_DIR):
mkdir $(OBJS_DIR)
$OBJS_DIR)/%.o : $(SRCS)
$(CXX) $(CPPFLAGS) -c $< -o $#
$(BIN_NAME) : $(OBJS)
$(CXX) -o $# $^
debug:
$(CXX) -g $(CPPFLAGS) -o $(BIN_NAME) $(OBJS)
.PHONY : all clean
clean:
$(RM) $(OBJS) $(OBJS_DIR)
dist-clean: clean
$(RM) $(BIN_NAME)
How can I make it works?
This line $OBJS_DIR)/%.o : $(SRCS) sets the prerequisites of every file that matches $OBJS_DIR)/%.o to all the files in $(SRCS) that's not even close to what you want. (It is also a typo. You are missing the opening ().
You can't write a single rule for what you are trying to do here you need three pattern rules (or one with a vpath/VPATH setup).
$(OBJS_DIR)/%.o: %.cpp
$(CXX) $(CPPFLAGS) -c $< -o $#
$(OBJS_DIR)/%.o: actor/%.cpp
$(CXX) $(CPPFLAGS) -c $< -o $#
$(OBJS_DIR)/%.o: lib/%.cpp
$(CXX) $(CPPFLAGS) -c $< -o $#
That being said you don't actually have any targets that match $(OBJS_DIR)/%.o since the value of $(OBJS) is Controller.o ... actor/Customer.o ... lib/Search.o. To fix that you also need:
OBJS=$(addprefix $(OBJS_DIR)/,$(patsubst %.cpp,%.o,$(notdir $(SRCS))))
$(notdir) to get just the filename from the source files.
$(patsubst) instead of $(subst) just for correctness (subst would have modified a Bar.cpp.cpp file to Bar.o.o).
$(addprefix) to add the $(OBJS_DIR) prefix to the bare object file names.
I'm trying to create a build system using make and would like to do the following:
have a list of source files specified in the makefile, e.g.
SOURCES = a.cpp b.cpp c.cpp
Automatically create build targets that depend on each file separately
I.e a single rule that would automatically expand into:
a.o: a.cpp
$(CC) $(CFLAGS) -c a.cpp -o a.o
b.o: b.cpp
$(CC) $(CFLAGS) -c b.cpp -o b.o
c.o: c.cpp
$(CC) $(CFLAGS) -c c.cpp -o c.o
I've tried the following:
SOURCES = a.cpp b.cpp c.cpp
OBJECTS = $(SOURCES:.cpp=.o)
$(OBJECTS): $(SOURCES)
$(CC) $(CFLAGS) -c $< -o $#
However, this seems to expand into the following
a.o: a.cpp b.cpp c.cpp
$(CC) $(CFLAGS) -c a.cpp -o a.o
b.o: b.cpp b.cpp c.cpp
$(CC) $(CFLAGS) -c a.cpp -o b.o
c.o: c.cpp b.cpp c.cpp
$(CC) $(CFLAGS) -c a.cpp -o c.o
Which is not right
Is there a simple way to achieve the result that i wrote earlier?
Make already has built-in rules that convert a .cpp file to a .o file. Just write:
SOURCES = a.cpp b.cpp c.cpp
all: $(SOURCES:.cpp=.o)
and it will work. If you want to know how to write your own rules, read about implicit rules, in particular pattern rules.
Say that I have two variables in Makefile
CXXFILES = a.cpp b.cpp
OBJFILES = a.o b.o
I would like to write a rule that will expand to
a.cpp : a.o
g++ -o a.o a.cpp
b.cpp : b.o
g++ -o b.o b.cpp
Note that I'm not looking for
%.o : %.cpp
g++ -o $# $<
because I don't want to match all .cpp files -- I only want those files specified by a variable.
Sounds like a job for a Static Pattern Rule:
Here is an example, which compiles each of foo.o and bar.o from the
corresponding .c file:
objects = foo.o bar.o
all: $(objects)
$(objects): %.o: %.c
$(CC) -c $(CFLAGS) $< -o $#