CODEWITHSUNDEEP
cmakefile
KTF
KTF

Reputation: 3

Makefile for Multiple Executables

I'm struggling to create a makefile for two executables

I want to be able to create a makefile that builds everything and then executes exec1 and exec2

I've got the following files with the headers included

array.c: array.h const.h

exec1.c: exec1.h array.h

exec2.c: exec2.h array.h

What I currently have for my makefile is:

MAINS = exec1 exec2
OFILES = exec1.o exec2.o

all: $(MAINS)
$(MAINS): %: %.o array.h const.h
    gcc -o $@ $^
$(OFILES): %.o: %.c %.h array.h const.h
    gcc -c %.c
array.o: %.c const.h
    gcc -c %.c

But it's not working. It says there's undefined references to some of the functions defined in array.h

Upvotes: 0

Views: 73

Answers (2)

dbush
dbush

Reputation: 223689

Your makefile format won't work like that. Try this instead:

MAINS = exec1 exec2

all: $(MAINS)

# define source dependencies for each object file
exec1.o: exec1.c exec1.h array.h
exec2.o: exec2.c exec2.h array.h
array.o: array.c array.h const.h

# build for exec1 with object file dependencies
# $@ = the target to build
# $^ = the dependencies
exec1: exec1.o array.o
    gcc -o $@ $^

# build for exec2 with object file dependencies
exec2: exec2.o array.o
    gcc -o $@ $^

# generic build for object files
# $< = the source filename matching the object file
%.o: %.c
    gcc -c $<

clean:
    rm -f exec1 exec2 exec1.o exec2.o array.o

Upvotes: 0

Lucas Streanga
Lucas Streanga

Reputation: 479

Question is a bit unclear on what the error here is, but I will try to guess. "Undefined reference" is not a Makefile issue, but rather is an issue when using GCC. We cannot see the code, but generally this means you referred to a function or variable that the compiler/linker cannot find. When linking, be sure to link all object files together:

gcc -o outputfile obj1.o obj2.o

Be sure to include function prototypes of all functions used outside of the original source file:

main.c:

#include"foo.h"

int main(void)
{
  foo();
  return 0;
}

foo.c:

void foo()
{
  /*implementation*/
}

foo.h:

void foo();

Compile:

gcc -c foo.c -o foo.o
gcc -c main.c -o main.o
gcc main.o foo.o -o MyProgram

Upvotes: 1

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