CODEWITHSUNDEEP
makefilegnu-make
ksp0422
ksp0422

Reputation: 349

how Makefiles work exactly

I'm writing a code for my gtk application written in C, and have some questions about it.

# Compiler
CC = gcc
CFLAGS = -Wall -g -o
RM = rm -f

# ADDITIONAL HEADER PATH 
GTKINC = `pkg-config --cflags gtk+-3.0`
GTKLIB = `pkg-config --libs gtk+-3.0` 

INC = $(GTKINC)
LIBLNK = $(GTKLIB)


# SOURCES, OBJECTS, EXECUTABLE
SRCS = hello.c
OBJS = $(SRCS:.c = .o)
EXEC = hello

.PHONY: clean

all: $(EXEC)
    @echo compile complete 

$(EXEC): $(OBJS)
    $(CC) $(INC) $(CFLAGS) $(EXEC) $(OBJS) $(LIBLNK)

clean:
    $(RM) *.o *~ $(EXEC)

previously, when I wrote Makefiles,I added lines for each object files

for example

blah blah

a.o: 1.h A.c B.c
        $(CC) blah blah
blah blah

and then, I got a little lazy and tried to do make something more easy-to-modify file googling up, and finally the product is the above code. 1. Does this actually do the same thing as what I did previously?(like in the example) I found out the code compiles properly, but I'm not sure if it checks out-of-date object files.(which is the whole meaning of 'make')
2. do you have to use 'depend' on header files in order to check out-of-date source files?? 3. it's a bit out of subject, but what's the difference between gcc -o hello.o hello.h hello.c and gcc -c hello.c ?

Upvotes: 0

Views: 128

Answers (1)

Maxim Egorushkin
Maxim Egorushkin

Reputation: 136256

2. do you have to use 'depend' on header files in order to check out-of-date source files

You should auto-generate dependencies on header files. See https://stackoverflow.com/a/9598716/412080

Upvotes: 1

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