Date:         Fri, 10 Aug 2001 11:43:26 -0700
Reply-To:     Dale McLerran <dmclerra@MY-DEJA.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Dale McLerran <dmclerra@MY-DEJA.COM>
Subject:      Re: Macro "array" warnings
Comments: To: rpearce@u.washington.edu
Content-Type: text/plain

Rachel,

Here is what the macro processor is doing when it scans the code

  %if %index(%str(%upcase(&took&j)),%upcase(&supp&i))>0 %then %do;

The processor looks from left to right, examining each token as it
goes.  Now, it comes to the token &took.  This token cannot be
resolved.  There is no variable &took, so you get the error message.

Now, if you prefix another ampersand to &took&j, so that you have
&&took&j, here is what the macro processor will do.  It will scan
from left to right as before.  When the double ampersand is
encountered, then the double ampersand will resolve to the token &.
The token took will resolve to took.  And the token &j will resolve
to the value of macro variable j.  Let's suppose that the value of
macro variable j is 3.  Then piecing these tokens together, you will
get the token &took3.  After the macro processor has finished the
first tokenization, it does another pass to see if there are any
more tokens to resolve.  On the second pass, the macro processor
finds the token &took3 which can now be resolved to the value of
macro variable took3.

So the fix to your problems is to use double ampersands:

  %if %index(%str(%upcase(&&took&j)),%upcase(&&supp&i))>0 %then %do;

Dale


>Date:         Fri, 10 Aug 2001 10:46:05 -0700
>Reply-To: Rachel Pearce <rpearce@U.WASHINGTON.EDU>
> Rachel Pearce <rpearce@U.WASHINGTON.EDU>      Macro "array" warnings SAS-L@LISTSERV.UGA.EDU
>Hello all,
>
>I wonder if someone can help me with this simple but annoying problem.
>I am probably doing something fundamentally wrong, but here goes:
>
>I have defined an "array" of macro variables  took1.... took9,
>and another array supp1...supp60.
>Now when I want to look at these variables and compare them, I do things
>like:
>
>    %if %index(%str(%upcase(&took&j)),%upcase(&supp&i))>0 %then %do;
>
>Now this gets me in *lots* of trouble as I get warning messages:
>
>WARNING: Apparent symbolic reference TOOK not resolved.
>WARNING: Apparent symbolic reference SUPP not resolved.
>
>Now of course they are not resolved, it is the subscripted "array" I want
>resolved, but as these %ifs are inside loops I get thousands and thousands
>of
>warning messages, and consequently either fill the log window or get huge
>unreadable log files. Can I avoid these messages somehow? Is there something
>wrong with my macro variable referencing?
>
>Rachel




---------------------------------------
Dale McLerran
Fred Hutchinson Cancer Research Center
mailto: dmclerra@fhcrc.org
Ph:  (206) 667-2926
Fax: (206) 667-5977
---------------------------------------

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