libpq and Datums management with embedded C function

I'm dealing witch a C function embedded into postgresql-9.0.2.

I'm returning a set of rows and following the example here
http://www.postgresql.org/docs/9.0/static/xfunc-c.html everything works
fine, but only if I use the C string approach.

I'm using libpq to retrieve data and something like this works fine:
snprintf(values[0], 16, "%s", PQgetvalue(funcctx->user_fctx, call_cntr, 0));
because PQgetvalue returns an array of char.

But if I want to get the original data as output, I have to deal with
Datums and I don't know how to do this with lippq.
Something like the following it doesn't work:

Datum values[1];
values[0] = (Datum) PQgetvalue(funcctx->user_fctx, call_cntr, 1);
snprintf(values[0], 16, "%s", PQgetvalue(funcctx->user_fctx, call_cntr, 0));

Have you got any idea of how to solve this...do you know another way to
perform a query indide the db without involve libpq?
I would prefer to use them because I can connect to several postgresql
instances.

Thank you.

--
Alessandro Candini

MEEO S.r.l.
Via Saragat 9
I-44122 Ferrara, Italy
Tel: +39 0532 1861501
Fax: +39 0532 1861637
http://www.meeo.it

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