[maemo-developers] Undefined reference error

[From: David King]

On 2010-05-14 01:54, Pallavi Kandhare <pallavi.kandhare at yahoo.com> wrote:
>Hi David,
> 
>My problem with that project is solved. I included .c files in Makefile.am

It is good to hear that! I sent this reply to the mailing list also, so 
that the discussion can be followed there.
 
>Now i have a new project with only 1 .c file ie. main.c
>
>Now, when i include third party libraries (hal/libhal.h and hal/libhal-storage.h) in my main.c  i again get the same error as :
>
>/src/main.c undefined reference to function-name
> 
>For using libhal and libhal-storage is anything more to be added?

Yes, if you are using libhal and libhal-storage through pkg-config with 
autotools, then I guess that you have:

PKG_CHECK_MODULES([HAL], [libhal libhal-storage])

or similar in your configure.ac. If not, then you should add it. If you 
wish to use that library in your program (main.c in your case), then in 
your Makefile.am you probably have something like:

bin_PROGRAMS = my_program
my_program_SOURCES = src/main.c

You need to add:

my_program_CPPFLAGS = $(HAL_CFLAGS)
my_program_LDADD = $(HAL_LIBS)

The first line adds the correct preprocessor flags, found by 
pkg-config, so that the preprocessor can find the libhal and 
libhal-storage headers. The LDADD line adds the correct linker flags so 
that the linker can find the libhal and libhal-storage libraries, which 
should solve the undefined reference error that you have.

http://www.openismus.com/documents/linux/using_libraries/using_libraries

The above link explains in slightly more detail what I have briefly 
described.

>Pls note: I had a look at the links u specified which also contains configure.ac and Makefile.am
>But my ESbox already creates them for me.
 
You might be able to do the steps that I have described above 
automatically from within ESBox. Maybe someone who is more familiar 
with it could comment?
 
-- 
David King | http://amigadave.com/ | davidk at openismus.com