minimum c++ make file for linux

Question

I've looking to find a simple recommended "minimal" c++ makefile for linux which will use g++ to compile and link a single file and h file. Ideally the make file will not even have the physical file names in it and only have a .cpp to .o transform. What is the best way to generate such a makefile without diving into the horrors of autoconf?

The current dir contains, for example

t.cpp t.h

and I want a makefile for that to be created. I tried autoconf but its assuming .h is gcc instead of g++. Yes, while not a beginner, I am relearning from years ago best approaches to project manipulation and hence am looking for automated ways to create and maintain makefiles for small projects.

Solution 1

If it is a single file, you can type

make t

And it will invoke

g++ t.cpp -o t

This doesn't even require a Makefile in the directory, although it will get confused if you have a t.cpp and a t.c and a t.java, etc etc.

Also a real Makefile:

SOURCES := t.cpp
# Objs are all the sources, with .cpp replaced by .o
OBJS := $(SOURCES:.cpp=.o)

all: t

# Compile the binary 't' by calling the compiler with cflags, lflags, and any libs (if defined) and the list of objects.
t: $(OBJS)
    $(CC) $(CFLAGS) -o t $(OBJS) $(LFLAGS) $(LIBS)

# Get a .o from a .cpp by calling compiler with cflags and includes (if defined)
.cpp.o:
    $(CC) $(CFLAGS) $(INCLUDES) -c $<

Solution 2

Here is a generic makefile from my code snippets directory:

SOURCES=$(wildcard *.cpp)
OBJECTS=$(SOURCES:.cpp=.o)
DEPS=$(SOURCES:.cpp=.d)
BINS=$(SOURCES:.cpp=)

CFLAGS+=-MMD
CXXFLAGS+=-MMD

all: $(BINS)

.PHONY: clean

clean:
    $(RM) $(OBJECTS) $(DEPS) $(BINS)

-include $(DEPS)

As long as you have one .cpp source producing one binary, you don't need anything more. I have only used it with GNU make, and the dependency generation uses gcc syntax (also supported by icc). If you are using the SUN compilers, you need to change "-MMD" to "-xMMD". Also, ensure that the tab on the start of the line after clean: does not get changed to spaces when you paste this code or make will give you a missing separator error.

Solution 3

Have you looked at SCons?

Simply create a SConstruct file with the following:

Program("t.cpp")

Then type:

scons

Done!

Solution 4

Assuming no preconfigured system-wide make settings:

CXX = g++
CPPFLAGS =        # put pre-processor settings (-I, -D, etc) here
CXXFLAGS = -Wall  # put compiler settings here
LDFLAGS =         # put linker settings here

test: test.o
    $(CXX) -o $@ $(CXXFLAGS) $(LDFLAGS) test.o

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

test.cpp: test.h

Solution 5

a fairly small GNU Makefile, using predefined rules and auto-deps:

CC=c++
CXXFLAGS=-g -Wall -Wextra -MMD
LDLIBS=-lm
program: program.o sub.o
clean:
    $(RM) *.o *.d program
-include $(wildcard *.d)

View more solutions

Comments

[Martin York]

Make is great for simple projects (and for playing with). But maintaining a big project becomes difficult to do correctly (you can hodge podge it easily but correctly is hard). Use tools 'like scons' to build your make file

[RichieHH]

scons looks nice. Certainly easier than Autoconf.

[bltxd]

OMake is great and takes over when make shows its limits.

[David Nehme]

this also doesn't create any dependencies.

[Martin York]

Though I love fiddling with makefile (its a language unto itself). I think this is the best answer, but I think you need to expand this answer a bit to explain why using "SCons" is better than using Makefiles directly. I am convinced but there is not enough here to convice others.

[RichieHH]

But why do you have specific rule for t: ? It kind of defeats the point of having a cpp.o rule.

[RichieHH]

Again this his a specific line for test. Why?

[hazzen]

The t rule generates, from the .o files, the binary by calling the linker. If I had four sources [abcd].cpp and a binary named t, the rule would link all four of those generated objects into one executable.

[Alnitak]

because you always have to specify what the Makefile will actually build. With suitable global defs, you might just be able to say just "test:" in the file, but the file above is guaranteed to work regardless of any global rules or macros.

[JesperE]

If OMake had better support for out-of-source builds and could generate Visual Studio project, it would be very close to perfect.

[bltxd]

We do out-of-source builds with OMake here. There are a few things to know but otherwise it works (0.9.8.5).

[jdkoftinoff]

Oops! Sorry for the broken links. I moved it to github. github.com/jdkoftinoff/magicmake - that being said I use CMake now instead.

[KRoy]

all should be phony too .

[Daniel Stevens]

You should use CXX and CXXFLAGS for C++ files, rather than CC and CFLAGS. Source: GNU make implicit variables. Note that CPPFLAGS are for the C Pre-Processor, which applies to both C and C++.

[Daniel Stevens]

Agreed. The GNU Make documentation shows all being listed as .PHONY. Source: Phony Targets