Return value if table doesn't exist

In the C++ interface, if one sends a query to the backend (via
ExecTuplesOk()) about a table, how do you tell if the table doesn't
exist? It appears that ExecTuplesOk() simply returns PGRES_EMPTY_QUERY,
and ConnectionBad() returns false. The only way I can see to tell if the
table doesn't exist is by checking ErrorMessage(). That seems pretty
goofy. This is pgsql 7.1.3.

Any ideas?

Paul