Generic character types of gregex are unrecognised

[tks <tksmashiw gmail com>]

Hi.
As long as reading
http://library.gnome.org/devel/glib/stable/glib-regex-syntax.html , we
can use generic character types of gregex such like "\s", "\d" etc...,
but they are not recognized in my sample code.
===============================
#include <glib.h>
int main(int argc, char *argv[])
{
  GRegex *reg;
  GError *error = NULL;
  reg = g_regex_new ("\d\D\s\S\w\W",
                     0,
                     0,
                     &error);
  return 0;
}
========================
$ LANG=C gcc -g `pkg-config --cflags --libs glib-2.0` sample.c
sample.c:6:22: warning: unknown escape sequence '\d'
sample.c:6:22: warning: unknown escape sequence '\D'
sample.c:6:22: warning: unknown escape sequence '\s'
sample.c:6:22: warning: unknown escape sequence '\S'
sample.c:6:22: warning: unknown escape sequence '\w'
sample.c:6:22: warning: unknown escape sequence '\W'
=========================
How can I use them? Do I have to use verbose posix character classes instead?
I'm using glib-2.18.3 on Fedora 10 and glib seems to be compiled to
use internal version of PCRE.