Date: Thu, 24 Jan 2002 13:07:42 +0000
Reply-To: John Whittington <John.W@MEDISCIENCE.CO.UK>
Sender: "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From: John Whittington <John.W@MEDISCIENCE.CO.UK>
Subject: Re: initialization
In-Reply-To: <E16TiS2-0000Uo-00@relay1.netnames.net>
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At 12:52 24/01/02 +0100, Jim Groeneveld wrote (in part):
>Smoke,
>I would say, often, but far not always.
>An example of an automatic initialization as 0 is the sum statement:
>variable + expression; Another example is a RETAINed variable, which
>initially is initialized to missing by default, but which is not
>reinitialized at each iteration of the data step.
Maybe I misinterpreted the question - but, particularly in view of the
simple example that Smoke gave, I thought the question was about 'initial
initialisation' (not re-initialisation) and also was about the situation in
which there was nothing in the code (like a sum statement) which imposed an
initial value.
As I said, on the basis of my interpretation of the question, I could see
no possible alternative for SAS than to 'assume' a missing value. If a
variable is encountered only in, say, a PUT statement, or on the
right-hand-side of an assignment, there is surely no alternative to
treating its value as 'missing' - it clearly would not be appropriate to
assume any NON-missing value, and 'missing'+'non-missing' seem to cover the
entire spectrum of possibilities!
However, as I said, maybe I misinterpreted the question!
Kind Regards,
John
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