CODEWITHSUNDEEP
c++linuxunixmakefile
eduherminio
eduherminio

Reputation: 1684

How to compile with a makefile without deleting .o files?

I've no experience at all with makefiles, but I managed to get mine working. However, when I modify a file and want the new version to get compiled again, I've just noticed that I need to delete de .o file generated previously to make the new compilation (otherwhise, I am told that nothing can be done).

Is there any option that can be added to a makefile to make it replace an old .o (only if it is an older version) with the new one? Or, at least, that's what I think my solution could be.

Thanks in advance,

Eduardo

PD: Here you have my Makefile, in case you need it.

todo: Sensor Control Lista

#Ficheros de los que depende
Sensor: Sensor.o semaforo.o memocomp.o colamsg.o
    #Cómo crea esos ficheros
    g++ Sensor.o semaforo.o memocomp.o colamsg.o -o Sensor -lrt -lpthread

Control: Control.o semaforo.o memocomp.o colamsg.o
    g++ Control.o semaforo.o memocomp.o colamsg.o -o Control -lrt -lpthread

Lista: Lista.o semaforo.o memocomp.o colamsg.o
    g++ Lista.o semaforo.o memocomp.o colamsg.o -o Lista -lrt -lpthread

#Compilación de cada uno de esos ficheros
Sensor.o: Sensor.cpp semaforo.hpp memocomp.hpp colamsg.hpp
    g++ -c Sensor.cpp

Control.o: Control.cpp semaforo.hpp memocomp.hpp colamsg.hpp
    g++ -c Control.cpp

Lista.o: Lista.cpp semaforo.hpp memocomp.hpp colamsg.hpp
    g++ -c Lista.cpp

semaforo.o: semaforo.cpp semaforo.hpp
    g++ -c semaforo.cpp

memocomp.o: memocomp.cpp memocomp.hpp
    g++ -c memocomp.cpp

colamsg.o: colamsg.cpp colamsg.hpp
    g++ -c colamsg.cpp


#Elimina los ficheros creados previamente por el usuario ****
clean:
    rm /dev/shm/sem.1207*
    rm /dev/shm/1207*
    rm /dev/mqueue/1207*

Upvotes: 2

Views: 262

Answers (2)

Richard Hodges
Richard Hodges

Reputation: 69884

Usage: make [options] [target] ...
Options:
  -b, -m                      Ignored for compatibility.
  -B, --always-make           Unconditionally make all targets.
...etc

Upvotes: 1

Karoly Horvath
Karoly Horvath

Reputation: 96258

colamsg.o: colamsg.cpp colamsg.hpp
^target    ^dependencies

As long as all the dependencies are listed for each target, you don't have to do anything.

Make will notice that the object file is out of date.

Upvotes: 0

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