Date:         Fri, 27 Jul 2001 17:54:29 -0400
Reply-To:     Edward Heaton <HEATONE@WESTAT.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Edward Heaton <HEATONE@WESTAT.COM>
Subject:      Re: problem with characters in macro %if expression
Comments: To: Gabriel <gabo@ECON.BERKELEY.EDU>
Content-Type: text/plain; charset="iso-8859-1"

Gabriel;

I tried the following with the same unexpected results.

1    %macro test ;
2        %Let measure = FGT ;
3        %If &measure = GE %then %put measure is ge and measure is &measure
;
4    %mEnd test ;
5    %test
measure is ge and measure is FGT

However, by putting the two in quotes, I get nothing written to the log.

16   %macro test ;
17       %Let measure = FGT ;
18       %If "&measure" = "GE" %then %put measure is ge and measure is
&measure ;
19   %mEnd test ;
20   %test

Now, if I change the pass value to GS I get nothing written to the log.

31   %macro test ;
32       %Let measure = FGT ;
33       %If &measure = GS %then %put measure is ge and measure is &measure
;
34   %mEnd test ;
35   %test ;

Ah!  I'm starting to get the picture.  SAS allows the old FORTRAN comparison
operators
{EQ,NE,GT,LT,GE,LE}.  So, let's look more closely at your code.

Suppose I replace GE with LE.  Then I get no output.

36   %macro test ;
37      %Let measure = FGT ;
38      %If &measure = LE %then %put measure is ge and measure is &measure ;
39   %mEnd test ;
40   %test ;

So, SAS interpreted your code as

%If ( ( &measure = ) GE ) %then %put measure is ge and measure is &measure ;

So first it resolves ( &measure = ) to false (0) since FGT is not the same
as nothing.

41   %macro test ;
42      %Let measure = FGT ;
43      %If &measure = %then %put measure is ge and measure is &measure ;
44   %mEnd test ;
45   %test ;

Then SAS compares the false value (0) to a blank value and determines that
the 0 is greater than the blank (It is obviously not equal to a blank.).

26   %macro test ;
27      %Let measure = FGT ;
28      %If 0 GE %then %put measure is ge and measure is &measure ;
29   %mEnd test ;
30   %test ;
measure is ge and measure is FGT

Thanks, this was a good exercise.

Ed

Edward Heaton, Senior Systems Analyst,
Westat (An Employee-Owned Research Corporation),
1550 Research Boulevard, Room 2018, Rockville, MD 20850-3195
Voice:  (301) 610-4818                      Fax:  (301) 294-3992
mailto:EdwardHeaton@westat.com              http://www.westat.com


-----Original Message-----
From: Gabriel [mailto:gabo@ECON.BERKELEY.EDU]
Sent: Friday, July 27, 2001 4:41 PM
To: SAS-L@LISTSERV.UGA.EDU
Subject: problem with characters in macro %if expression


I have a problem using logical expressions with the macro language. I
have a line like this within a macro:

%IF &MEASURE=GE %then %put measure is ge and measure is &measure;

Now I know the macro variable MEASURE is set to FGT. When I run that
line with options symbolgen selected, I get the following inthe log
file:

SYMBOLGEN:  Macro variable MEASURE resolves to FGT
SYMBOLGEN:  Macro variable MEASURE resolves to FGT
measure is ge and measure is FGT

Why does SAS seem to think that &MEASURE=GE, when the output says
otherwise?
Thanks for the help!
Gabriel