Date:         Tue, 30 Sep 2003 12:11:25 -0700
Reply-To:     "Choate, Paul@DDS" <pchoate@DDS.CA.GOV>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         "Choate, Paul@DDS" <pchoate@DDS.CA.GOV>
Subject:      Re: if(), while (), until() - short circuit evaulation ?
Comments: To: "Fehd, Ronald J. (PHPPO)" <rjf2@CDC.GOV>

And order the conditions by least-likelihood:

if     State='RI' then
   if  State='NY' then ...

Paul Choate
DDS Data Extraction
(916) 654-2160

This isn't right, this isn't even wrong
-- Wolfgang Pauli

-----Original Message-----
From: Fehd, Ronald J. (PHPPO) [mailto:rjf2@CDC.GOV]
Sent: Tuesday, September 30, 2003 11:03 AM
To: SAS-L@LISTSERV.UGA.EDU
Subject: Re: if(), while (), until() - short circuit evaulation ?

> From: Richard A. DeVenezia [mailto:radevenz@IX.NETCOM.COM]
> In DATA Step, does the while () clause (or I suppose eval in
> generation ...
> if() until(), etc...) use short circuit testing ?
>
> i.e.
> A=1
> B=2
>
> if (A=1 or B=2) then ... else ...
> if short-circuit evaluation then the then clause should run
> without having to test B=2
>
> if (A=0 and B=2) then ... else ...
> if short-circuit evaluation then the else clause should run
> without having to test B=2

I'm not sure, probably need a Little Birdy to comment on that.

however, one of the optimizing tricks in
SAS Programming Tips: A Guide to Efficient SAS Processing
is
to replace
if A=1 and B=2 then
with
if     A=1 then
   if  B=2 then ...

you are highly discouraged from using else with this construction
as will be immediately evident upon careful thought.
%-|

Ron Fehd  the logical maven  CDC Atlanta GA USA RJF2@cdc.gov

By using your intelligence
you can sometimes make your problems twice as complicated.
-- Ashleigh Brilliant

If you always try to be logical,
you probably won't ever have much sorrow,
or much fun.
-- Ashleigh Brilliant pot-shot #4438