GTK+ compilation undefined reference C

问题:

I'm trying to compile and link a simple program downloaded from the web to learn how to make a GUI using the gtk+ library.

Here is my makefile:

CC = gcc
BIN = gtk_led
SRC = main.c gtkled.c
OBJ = main.o gtkled.o

CPPFLAGS =-Wall -W -ansi -pedantic -O2 `pkg-config --cflags gtk+-2.0`

LDFLAGS = `pkg-config --libs gtk+-2.0`

all: $(BIN)

$(BIN): $(SRC)
$(CC) $(CPPFLAGS) -c $(SRC)
$(CC) $(LDFLAGS) -o $(BIN) $(OBJ)

clean:
rm -f *.o *~ core $(BIN)

When I do make, the build fails with the following errors:

gtkled.o: In function `gtk_led_size_allocate':
gtkled.c:(.text+0x43a): undefined reference to `g_return_if_fail_warning'
gtkled.c:(.text+0x487): undefined reference to `gdk_window_move_resize'
gtkled.o: In function `gtk_led_size_request':
gtkled.c:(.text+0x4f5): undefined reference to `g_return_if_fail_warning'

So I don't understand why.... I'm new to Linux, so that's hard for me :) (On ubuntu, working with virtualBox)

Thanks.

回答1:

Dont use backquotes in Makefile-s (but use the shell function of GNU make). And GTK2 is obsolete, why not use GTK3?

Replace at least the two lines CPPFLAGS and LDFLAGS with

 PACKAGES= gtk+-3.0
 OPTIMFLAGS=-g # put -O2 when all is ok
 PKG_CFLAGS= $(shell pkg-config  --cflags $(PACKAGES))
 CPPFLAGS =-Wall -W -ansi -pedantic $(OPTIMFLAGS) $(PKG_CFLAGS)
 LDFLAGS = $(shell pkg-config --libs $(PACKAGES))

BTW, you probably mean CFLAGS not CPPFLAGS. Run make -p to understand what are the builtin rules known to make; see also this answer and that answer to some related questions...

Also, order of arguments to gcc matters a lot, so

 $(CC) $(LDFLAGS) -o $(BIN) $(OBJ)

is wrong, you probably want

 $(CC) $(OBJ) $(LDFLAGS) -o $(BIN)