Date:         Wed, 16 Nov 2005 13:13:12 -0500
Reply-To:     Ed Heaton <EdHeaton@WESTAT.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Ed Heaton <EdHeaton@WESTAT.COM>
Subject:      Re: QUERY: Construction of variable-dimension arrays using macro
              variables
Comments: To: stephan.rudolfer@manchester.ac.uk
Content-Type: text/plain; charset="us-ascii"

Stephen,

You have substantial problems if you want to generate this code on a
single pass through the DATA step.  The problem is that the ARRAY
statement is a compile-time statement and the assignment statement is a
run-time statement.  DATA steps are compiled before they are run.

You attempted to pass your data through a %LET statement.  However, %LET
statements are global and hence executed immediately after they are read
(i.e., before compilation).  So, once again, your run-time data is not
available.

A two-step process might be in order.  Only you and your task know for
sure.

Data _null_ ;
    Len=5 ;
    Call symPut( "varLen" , compress( put( len , best. ) ) ) ;
Run ;
Data try ;
    Array element[*] a1-a&varlen ;
Run;

Ed

Edward Heaton, SAS Senior Systems Analyst,
Westat (An Employee-Owned Research Corporation),
1600 Research Boulevard, RW-4541, Rockville, MD 20850-3195
Voice: (301) 610-4818                  Fax: (301) 294-3879
mailto:EdHeaton@Westat.com             http://www.Westat.com


-----Original Message-----
From: owner-sas-l@listserv.uga.edu [mailto:owner-sas-l@listserv.uga.edu]
On Behalf Of Stephan Rudolfer
Sent: Wednesday, November 16, 2005 10:58 AM
To: SAS(r) Discussion
Cc: Stephan Rudolfer
Subject: QUERY: Construction of variable-dimension arrays using macro
variables


Let len denote a positive integer.  I wish to create an array of
dimension len.  There is a problem here: to create an array, we have to
specify the first and last elements in the array.  However, here the
number is a variable, and SAS doesn't seem able to accept an array
element of the form a&len.  Naively, I've tried the following code:

Data try;
Len=5;
%let varlen=len;
Array element(len) a1-a&varlen;
Run;

This generates the following log file:

153  data try;
154  len=5;
155  %let varlen=len;
156  %let last=lot&varlen;
SYMBOLGEN:  Macro variable VARLEN resolves to len
157  array element(len)
157! a1-a&varlen;
SYMBOLGEN:  Macro variable VARLEN resolves to len
ERROR: Missing numeric suffix on a numbered variable list (a1-alen).
WARNING: Defining an array with zero elements.
158  run;

What I was hoping was that the macro substitution would generate
a-len=a5.

Any suggestions would be most gratefully received.