Check that numeric is zero

"Gabriel" == Gabriel Furstenheim Milerud <furstenheim@gmail.com> writes:

Gabriel> Hi,

Gabriel> I'm writing a Postgres native extension and I would like to
Gabriel> check that a numeric is zero.

Gabriel> My problem is that all exported methods like numeric_eq or
Gabriel> numeric_sign require me to have a numeric to start with, and
Gabriel> const_zero is not exported in numeric.c.

Currently the easiest and most portable way to get a numeric constant is
to call int4_numeric or int8_numeric via DirectFunctionCall; if you
don't care about versions older than pg14 there's also int64_to_numeric
which can be called directly from C.

Datum zero_num = DirectFunctionCall1(int4_numeric, Int32GetDatum(0));

(remember that this will be allocated in the current memory context; if
you want to keep a copy long-term, you'd want to datumCopy it somewhere
else.)

--
Andrew (irc:RhodiumToad)