CODEWITHSUNDEEP
c++makefile
Jacob Garby
Jacob Garby

Reputation: 855

Makefile not building objects how I'm telling it to

This is my project directory file tree:

.
├── entity.cpp
├── entity.hpp
├── entitytypes.hpp
├── main.cpp
├── Makefile
├── player.cpp
└── player.hpp

Makefile's contents is this:

CC=g++
CFLAGS=-Wall -pg
LDFLAGS=-lsfml-graphics -lsfml-window -lsfml-system
EXE=gametest

all: $(EXE)

%.o: %.c
    $(CC) -c $< -o $@ $(CFLAGS)

$(EXE): main.o entity.o player.o
    g++ $^ -o $@ $(LDFLAGS)

And very oddly, this is the output when I type make:

g++    -c -o main.o main.cpp
g++    -c -o entity.o entity.cpp
g++    -c -o player.o player.cpp
g++ main.o entity.o player.o -o gametest -lsfml-graphics -lsfml-window -lsfml-system

So as you can see, the last line of the output corresponds to the $(EXE) section of the Makefile. It's linking the program with the correct flags, etc. My problem is that when each individual object file is build, it's not at all taking into account my %.o: %.c rule. This is clear since when it builds the objects, there is a long gap between g++ and -c, which I didn't write. Also, it's missing out my $(CFLAGS). Even weirder, when I comment out the %.o: %.c section, the Makefile does the exact same thing.

It seems to me like it's using some kind of default build command, and just ignoring mine.

I've looked at Makefiles I've written in the past which as far as I can tell use the exact same macros in the same way, so I'm very confused as to why this is happening.

Upvotes: 1

Views: 516

Answers (3)

Toby Speight
Toby Speight

Reputation: 30781

The built-in %.o: %.cpp rule uses CXX (not CC) to specify the compiler, and CXXFLAGS (not CFLAGS) for the flags. So re-write your Makefile to set those variables, and you don't need to specify the pattern rule yourself:

CXX = g++
CXXFLAGS = -Wall -Wextra -pg
LIBS = -lsfml-graphics -lsfml-window -lsfml-system

gametest: main.o entity.o player.o
gametest: LINK.o = LINK.cc

Upvotes: 1

Galik
Galik

Reputation: 48615

It looks like a half converted Makefile for C. It uses the wrong variables and looks for C files rather than C++. Try this (untested):

CXX := g++
CXXFLAGS := -Wall -pg
LDFLAGS := -lsfml-graphics -lsfml-window -lsfml-system
EXE := gametest

all: $(EXE)

%.o: %.cpp
    $(CXX) -c $(CXXFLAGS) -o $@ $< 

$(EXE): main.o entity.o player.o
    $(CXX) -o $@ $^ $(LDFLAGS)

C++ uses CXX whereas C uses CC, same with CXXFLAGS.

Note: Remember the indentations are TABs not spaces!

Upvotes: 2

adrtam
adrtam

Reputation: 7211

You named your files as *.cpp while your rules said *.c, that's why.

Upvotes: 3

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