Date:         Thu, 19 Nov 1998 09:19:28 -0500
Reply-To:     WHITLOI1 <WHITLOI1@WESTAT.COM>
Sender:       "SAS(r) Discussion" <SAS-L@UGA.CC.UGA.EDU>
From:         WHITLOI1 <WHITLOI1@WESTAT.COM>
Subject:      Re: A macro looping error
Comments: To: "Raymond V. Liedka" <liedka@UNM.EDU>
Content-Type: text/plain; charset=US-ASCII

   Subject: A macro looping error
   Summary: ;
   Respondent: Ian Whitlock <whitloi1@westat.com>
 
   Raymond V. Liedka <liedka@UNM.EDU> wondered what was wrong with his
   macro code:
 
   > 1
   > 2          %macro words(string);
   > 3                  %local count word;
   > 4                  %let count=1;
   > 5                  %let word=%qscan(&string,&count,%str(  ));
   > 6                  %do %while(&word ne);
   > 7                          %let count=%eval(&count+1);
   > 8                          %let word=%qscan(&string,&count,%str( ));
   > 9                  %end;
   > 10                 %eval(&count-1);
   > 11         %mend words;
   > 12
   > 13
   > 14         %macro makedata;
   > 15
   > 16
   > 17         %let varlist=
   > 18         TOP.CP.$.GNP.PCAP
   > 19         TOP.KP.$.GNY.PCAP
   > 20         TOP.KP.$.GDI.PCAP
   > 21         CP.$.GNP.CAP
   > 22         PR.POPN
   > 23         NET.INVEST.DIRECT
   > 24         ;
   > 25
   > 26         %let nvars=%words(&varlist);
   > 27
   > 28
   > 29         %do i=1 %to &nvars;
   > 30                 %let thisvar=%qscan(&varlist,&i,%str( ));
   > 31                 %put &thisvar;
   > 32         %end;
   > 33
   > 34         %mend makedata;
   > 35
   > 36         %makedata;
   >
   > ERROR: A character operand was found in the %EVAL function or %IF
   >
 
   Diane Rhodes <RHODESD1@WESTAT.COM> and Peter Crawford
   <Peter@CRAWFORDSOFTWARE.DEMON.CO.UK> both gave solutions to his "real"
   problem, but I am more interested in why the macro code did not work.
 
   Stan Li <sas_sph@YAHOO.COM> made the same mistake in his improved
   word counter:
 
   >   %macro words(string);
   >   %* to count the words in the input string;
   >      %eval(%length(&string)-
   >          %length(%sysfunc(compress(&string))) + 1);
   >   %mend words;
 
   There is no looping error.  The mistake is on line 10.  The macro
   WORDS should produce a count.  As given it produces a count plus a
   semicolon.  Unfortunately I cannot find a plausible explanation why
   the extra semicolon should cause line 26 to fail, but it does.  Can
   anyone explain why?
 
   Ian Whitlock