Makefile中的相应依赖项和目标列表

Question

In a makefile, suppose I have two corresponding dependency and target lists, like this:

SRC = x.c y.c z.c
OBJS = x.o y.o z.o

Of course, my example is more complicated than this, but I want to know if it is possible to automatically create targets xo, yo, zo depending on xc, yc, zc respectively, like this:

x.o: x.c
y.o: y.c
z.o: z.c

Answer 1

You can use substitution references :

OBJS = $(SRC:.c=.o)

or patsubst :

OBJS = $(patsubst %.c,%.o,$(SRC))

Answer 2

I think the question was how to create rules for each of these targets, not how to create OBJS from SRC (although it's good to do that!).

The simplest way is to use the already-built-in rule in make that knows how to do it; you don't need to write your own. Just use:

all: $(OBJS)

and they'll all be created. You can control the compiler by setting the CC variable, the preprocessor flags by setting the CPPFLAGS variable, and the other compiler flags by setting the CFLAGS variable.

If you DO really want to write your own rule, then pattern rules will do that for you easily:

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