Date:         Fri, 3 Nov 2000 14:09:41 -0800
Reply-To:     kmself@IX.NETCOM.COM
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         kmself@IX.NETCOM.COM
Subject:      Re: implied RETURN
In-Reply-To:  <F165wdUTaGmvSVMum030000a0f2@hotmail.com>; from
              paul_dorfman@hotmail.com on Fri, Nov 03, 2000 at 09:05:09PM +0000
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on Fri, Nov 03, 2000 at 09:05:09PM +0000, Paul Dorfman (paul_dorfman@hotmail.com) wrote:
> >_N_ equals zero *prior* to the first iteration of the data step loop.
> 
> Karsten,
> 
> I *guess* that prior to... _n_ is rather missing, or, most probably, just 
> compgarbage. Which does not really matter, for the next internal counter 
> value gets *moved* into _n_ by the first internal instruction in each 
> iteration.

Getting fuzzy-headed in my old age.  Yeah, what I said didn't make
sense.

Jack Hamilton's probably to blame for me picking up the '_n_ eq 0'
idiom, as I worked under him for a while.

Certain SAS statements, principally SET and OUPUT, have both executable
and non-executable components.  The non-executable component is the
initialization of the program data vector, and of output datasets.  This
initialization occurs so long as the statement is in non-commented code,
whether or not the statement is actually reachable in data step
operation.

As noted, the construct 'if _n_ eq 0 then' syntax is equivalent to 'if
FALSE_CONDITION do' -- the conditional code is never executed.  However,
a SET, MERGE, UPDATE, OUTPUT, or similar statement will be initialized.

Jack, back to you.

-- 
Karsten M. Self <kmself@ix.netcom.com>     http://www.netcom.com/~kmself
 Evangelist, Zelerate, Inc.                      http://www.zelerate.org
  What part of "Gestalt" don't you understand?      There is no K5 cabal
   http://gestalt-system.sourceforge.net/        http://www.kuro5hin.org

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