At Sun, 22 Sep 2019 23:02:04 -0300, Alvaro Herrera <alvhe...@2ndquadrant.com> wrote in <20190923020204.GA2781@alvherre.pgsql> > On 2019-Sep-22, Dmitry Dolgov wrote: > > > > I think multiplying two ScanDirections to watch for a negative result is > > > pretty ugly: > > > > Probably, but the only alternative I see to check if directions are > > opposite is > > to check that directions come in pairs (back, forth), (forth, back). Is > > there > > an easier way? > > Maybe use the ^ operator?
It's not a logical operator but a bitwise arithmetic operator, which cannot be used if the operands is guaranteed to be 0 or 1 (in integer). In a-kind-of-standard, but hacky way, "(!a != !b)" works as desired since ! is a logical operator. Wouldn't we use (a && !b) || (!a && b)? Compiler will optimize it some good way. regards. -- Kyotaro Horiguchi NTT Open Source Software Center
