Can not use howto with c++

Hi,
Now, I find a good method to make use of gnuradio blocks with c++
and without python. I get it from
http://gnuradio.org/redmine/repositories/browse/gnuradio/gnuradio-examples/c++/dial_tone.
So , after install gr-howto-write-a-block successfully, I want to
test the block with c++ as the example of dial_tone.
But , I run into a stone wall. here is my code:
#include
#include
#include <gr_top_block.h>
#include <gr_io_signature.h>
#include <gr_vector_source_f.h>
#include <gr_vector_sink_f.h>
#include <howto_square_ff.h>
int main()
{
std::vector data_source;
float f[5] = {-3, 4, -5.5, 2, 3};
for (int i = 0; i < 5; i++)
{
data_source.push_back(f[i]);
}
gr_top_block_sptr tb = gr_make_top_block(“topblock”);
gr_vector_source_f_sptr src =
gr_make_vector_source_f(data_source,false, 5);
howto_square_ff_sptr howto_square = howto_make_square_ff();
gr_vector_sink_f_sptr dst = gr_make_vector_sink_f(5);
tb->connect(src,0, howto_square,0);
tb->connect(howto_square, 0, dst,0);
tb->run();
return 0;
}
I have add the _howto.so ‘s path.
“-L…/gr-howto-write-a-block-3.2.2/src/lib/.libs” and “-l_howto”
when I start “make”, then it turn up linker error as followed:
/usr/bin/ld: cannot find -l_howto
collect2: ld returned 1 exit status
make: *** [howto] error 1
after compare with gnuradio-core’s libgnuradio-core.so format, I copy
the _howto.so to the path …/gr/lib and rename it as libhowto.so and
use “-lhowto”
then, I “make” again, then it turn up linker error as followed:
/work/project/keywie_11p/gr/lib//libhowto.so: undefined reference to
PyTuple_SetItem' /work/project/keywie_11p/gr/lib//libhowto.so: undefined reference to PyExc_ValueError’
/work/project/keywie_11p/gr/lib//libhowto.so: undefined reference to
PyLong_AsLong' /work/project/keywie_11p/gr/lib//libhowto.so: undefined reference to _PyInstance_Lookup’
/work/project/keywie_11p/gr/lib//libhowto.so: undefined reference to
PyObject_GetAttr' /work/project/keywie_11p/gr/lib//libhowto.so: undefined reference to PyObject_Call’
/work/project/keywie_11p/gr/lib//libhowto.so: undefined reference to
`PyExc_IndexError’

what’s wrong with this case? The howto block could not use directly in
c++ as gr_sig_source_f or audio_alsa_make_sink, isn’t it ? Or, I have
made a mistake ?

thanks
best wishes!