Thread: Easy Makefile Test

I want to have makefiles for both c and c++ in different file folder locations. The c makefile here was nice and easy (the file needs to be called Exercises.c for this makefile...I did not set it up so that I can rename it with an environment variable). My question is, how come the c++ makefile is more difficult. I could not make it very simple like the c makefile, I had to do it a lot differently. Is there an easier way to do the c++ makefile (the file for the c++ makefile needs to be called Exercises.cpp).

The C Makefile:

Code:

P=Exercises
OBJECTS=
CFLAGS= -g -Wall -o3 -std=gnu11
LDLIBS=
CC=gcc

$(P): $(OBJECTS)

The C++ Makefile

Code:

P=Exercises
OBJECTS= 
CPPFLAGS= 
CXXFLAGS= 
LDLIBS= 
CXX=g++

$(P): $(P).o
    g++ -g -o $@ $(P).o

$(P).o : $(P).cpp
    g++ -g -Wall -std=gnu++14 -c $(P).cpp

clean:
    rm $(P).o $(P)

I updated the C++ makefile. It is a bit better this way: Anyway, it appeared that I had to use two lines because the -c option compiled the code but did not link, whereas with gcc the flags do both the compile and the link and there isn't even an object file because it automatically takes both steps.

Code:

P=Exercises
OBJECTS= 
CPPFLAGS= 
CXXFLAGS= 
LDLIBS= 
CXX=g++

$(P): $(P).o
    g++ -g -o $@ $<

$(P).o : $(P).cpp
    g++ -g -Wall -std=gnu++14 -c $<

clean:
    rm $(P).o $(P)

This is more like the answer that I was looking for. I did not have the -o flag, so I could get it to compile into a .o file, but it would not link until I added that flag, and also the -c needed to be after the -o otherwise it would not work. Anyway, I should be able to set these other variables now and hopefully it will work out. It took a long time to figure out, btw Elysia, have you tried the Intel compiler? As far as the c++14 flag, I will look it up. When I looked up how to set up c++14, the search said to use gnu++14 and that did compile the variable in my code which I initialized with the new style. I would not know just how much of the new standard gnu++ supports.

Code:

P=Exercises
OBJECTS= 
CPPFLAGS= 
CXXFLAGS= -std=gnu++14 -g -Wall -o -c
LDFLAGS= 
LDLIBS= 
CXX=g++

$(P): $(OBJECTS)

clean:
    rm $(P)

And

Code:

#include <iostream>

using namespace std;

int main(){
    int n {12};
    
    cout << "Hello" << n << endl;
    return 0;
}

I'd recommend switching to an IDE that builds Makefiles for you. Code::Blocks doesn't use literal Makefiles but it'll still build for you.

Originally Posted by MutantJohn

I'd recommend switching to an IDE that builds Makefiles for you. Code::Blocks doesn't use literal Makefiles but it'll still build for you.

Also an excellent idea.

Yes I will still be spending a bit more time on Makefile and thanks for the info. I have Qt Creator set up however if I want an open source project than I need to use package config, auto tools, and Makefile. My next step however looks like I will be operating the debugger. I need the gnu side, but it should also be POSIX compatible.

I have to prepare to make an open source effort, although at this time I am just reading some books. What do you mean, I thought that gnu is the best. As a second language I will take python and it has lots of gnu libraries as far as I understand.

...wasn't quite finished talking.

I sort of just follow what the book that I am reading says to do, except that it does not tell me everything, right. I have a few different books that I am reading at this moment, one of them is a C book and that is why I wondered about Makefiles for the c++ compiler. It was not covered in my book. Gnu works okay for me and I've only heard of the Gnu Scientific Library so far. The Makefile lets me add more libraries to the compiler and linker via include paths and lib paths instead of typing them out manually every time I update my source files.

...and that is all that I know :+p

The Gnu option is my only choice here, I believe, and I almost have things under control now. I can see the path better now that I have blundered enough times. The Gnu is the light, to brighten the way it is full of peace, goodness, and fruitful experiences.