Re: Should casting to integer produce same result as trunc()

> -----Original Message-----
> From: Alban Hertroys [mailto:haramrae(at)gmail(dot)com]
> Sent: Wednesday, 12 October 2011 1:35 AM
> To: Tom Lane
> Cc: Harvey, Allan AC; pgsql-general(at)postgresql(dot)org
> Subject: Re: [GENERAL] Should casting to integer produce same
> result as trunc()
>
> On 11 October 2011 15:41, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> > Alban Hertroys <haramrae(at)gmail(dot)com> writes:
> >> On 11 Oct 2011, at 2:55, Harvey, Allan AC wrote:
> >>> My simple understanding of trunc() and casting to an
> integer says that
> >>> there is a bug here.
> >
> >> Which the type-cast should round to 4380103 and 4380104
> respectively.
> >> It doesn't:
> >
> > That's because a cast from float to int rounds, it doesn't truncate.
> >
> > regression=# select (4.7::float8)::int;
> >  int4
> > ------
> >    5
> > (1 row)
>
> I figured it would be something like that. Is that how it's defined in
> the SQL standard?
>
> All other programming languages I've come to know truncate floats on
> such casts (C, php, python, java, to name a few).
> This is probably quite surprising to people used to these languages.

Thanks guys, yes C/C++ is my poison, forming my expectations.

Allan

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