Обсуждение: newbie libpq question...

I'm trying to use the libpq library for the first time and I'm
experiencing what seems to be a very basic problem.  When I run the
following:
res = PQexec(conn, "select blah blah blah");test_int=PQntuples(res);fprintf(stdout,"number of rows:
%f\n",test_int);test_int=PQnfields(res);fprintf(stdout,"numberof cols: %f\n",test_int);
 

where "blah blah blah" is the selection criteria, I get zero rows and
zero columns.  When I do the exact same "select" query through the psql
interface I get 547 rows and 3 columns.  I've checked that
PQresultStatus = PGRES_TUPLES_OK, so it seems like it completed the
command correctly.  I'm new to postgres and I haven't used C in a long
while so I'm a little rusty there.  Am I missing something obvious?

thanks in advance for any insight,
dh

On Mon, Nov 08, 2004 at 05:23:59PM -0500, Doug Homoelle wrote:
> 
>     res = PQexec(conn, "select blah blah blah");
>     test_int=PQntuples(res);
>     fprintf(stdout,"number of rows: %f\n",test_int);
>     test_int=PQnfields(res);
>     fprintf(stdout,"number of cols: %f\n",test_int);
> 
> where "blah blah blah" is the selection criteria, I get zero rows and
> zero columns.

You're using floating-point (%f) conversions to print integers; use
%d or %i instead.  Some compilers have options to warn you of such
mistakes -- with gcc, for example, you can use -Wall.

-- 
Michael Fuhr
http://www.fuhr.org/~mfuhr/