RE: IF Coding question

["M. Lazarus" <mlazarus@xxxxxxxx>]

Bob,

At 3/30/04 09:28 PM, you wrote:
> I don't agree that negative conditional evaluations are "more
> straightforward" than positive logic that is prefixed with NOT.
> It is a known fact that the mind can interpret positive logic much quicker
> than negative.

 In both cases we are looking at a negative condition.  My criteria is to 
try to read it out loud.  My way reads like you would state it in English:

 If  TOT1a does not equal TOT2a or TOT1b does not equal TOT2bc...

 Putting the NOT, in this case, before the test is unnecessarily awkward, 
IMHO.


>   But, hey, we're not out to save the world with RPG IV, now are we. :)

 One line of code at a time...  :-)

 -mark

> -----Original Message-----
> From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx]
> On Behalf Of M. Lazarus
> Sent: Tuesday, March 30, 2004 7:41 PM
> To: RPG programming on the AS400 / iSeries
> Subject: RE: IF Coding question
>
> Bob,
>
>   I'm not sure if it's mandated or not (w/o checking the order of
> evaluation in the manual), but the following would be the preferable way to
> mimic the original code:
>
>     If       NOT ( TOT1a = TOT2a and TOT1b = TOT2bc )
>
>   Although, my preference would be:
>
>     If       TOT1a <> TOT2a Or TOT1b <> TOT2bc
>
>   since it's more straightforward.
>
>   -mark
>
> At 3/30/04 06:39 PM, you wrote:
> >It equates to this in RPG IV:
> >
> >    If       NOT TOT1a = TOT2a  and TOT1b = TOT2bc
> >    EXCEPT   HEADR
> >    EXCEPT   TOTAL
> >    ENDIF
> >
> >It is an old "trick" in RPGIII that allows you to do a set of opcodes when
> >something is NOT true. In other words, it is too hard to code the opposite
> >condition, so they coded it in "positive logic" and use the ELSE to reverse
> >the "polarity" of the conditional statement.
> >-Bob Cozzi
> >
> >
> >-----Original Message-----
> >From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx]
> >On Behalf Of simafrog
> >Sent: Tuesday, March 30, 2004 8:19 AM
> >To: RPG programming on the AS400 / iSeries
> >Subject: IF Coding question
> >
> >I am trying to understand the point/reason for this code:
> >       TOT1a   IFEQ TOT2a
> >       TOT1b   ANDEQTOT2bC
> >               ELSE
> >               EXCPTHEADR
> >               EXCPTTOTAL
> >               ENDIF
> >Why do you need the "IF" "AND" part? What purpose does this serve?
>
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