Why can't I build a "hello world" for glib?
So here's the world's simplest glib program:
#include <glib.h>
I try to compile it with gcc test.c and I get:
test.c:1:18: error: glib.h: No such file or directory
So I make sure that I have the right packages:
# dpkg -l | grep libglib
ii libglib-perl 1:1.183-1 Perl interface to the GLib and GObject libra
ii libglib1.2-dev 1.2.10-19build1 The GLib library of C routines (development)
ii libglib1.2ldbl 1.2.10-19build1 The GLib library of C routines
ii libglib2.0-0 2.20.1-0ubuntu2 The GLib library of C routines
ii libglib2.0-cil 2.12.1-1ubuntu2 CLI binding for the GLib utility library 2.1
ii libglib2.0-data 2.18.2-0ubuntu2 Common files for GLib library
ii libglib2.0-dev 2.20.1-0ubuntu2 Development files for the GLib library
ii libglibmm-2.4-1c2a 2.18.1-1 C++ wrapper for the GLib toolkit (shared lib
Then I search for any "glib.h" anywhere under /usr/include. I get two, /usr/include/glib-1.2/glib.h and /usr/include/glib-2.0/glib.h. So I try:
$ gcc -I/usr/include/glib-2.0 -Wall test.c
In file included from /usr/include/glib-2.0/glib/galloca.h:34,
from /usr/include/glib-2.0/glib.h:32,
from test.c:2:
/usr/include/glib-2.0/glib/gtypes.h:34:24: error: glibconfig.h: No such file or directory
(about 10,000 more errors snipped)
I don't seem to have a glibconfig.h anywhere on my computer.
What do I do now?
Answer
glib tends to hide itself... Your include statement doesn't work because GCC doesn't automatically search subdirectories, and so cannot see the glib.h in glib-1.2 or glib-2.0.
Read the Compiling GLib Applications page in the GLIB manuals... you use commands like pkg-config --cflags glib-2.0 to get the right flags for GCC.
The canonical way to do what you are trying is
% gcc test.c -Wall -o test `pkg-config --cflags --libs glib-2.0`
Note the back-ticks, which tell the shell to run the pkg-config command "in-place".