Date:         Thu, 4 May 2000 17:00:22 -0400
Reply-To:     Richard DeVenezia <radevenz@IX.NETCOM.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Richard DeVenezia <radevenz@IX.NETCOM.COM>
Organization: MindSpring Enterprises
Subject:      Re: XML Creation Macro

Shawn:

With these types of macros, they don't return values per-se.  The act of
invoking the macro simply generates 'text' that is replaced in the current
token stream being interpreted by the SAS executor.

So when the macro has the
&vexist
statement, the value of macro variable vexist replaces the %varexist(....).

Hence you can use this feature in several ways

In a macro assignment
%let rc = %varexist(...);

In a macro
%if (%varexist(...)) %then %do; ... %end;

In a data step
if %varexist(...) then do; .... end;
Note: In a data step, the value of a data step variable can not be passed to
the macro presented by John, since all macros are resolved before the data
step is compiled and run.
To do checks on tables and variables that are values of variables in a data
set, use the same functions ( open, close, varnum ) as the macro does.

You could even get funky and write a macro that is for use in data step
only.
e.g. (untested)
%macro dshasvar (dataset, variable);
%* generates data step code for use only in data step;
%* dataset - character: name of data set to examine;
%* variable - character: name of variable to check for in data set;
%* arguments are quoted text strings or data step character expressions;

%* your data step should not have variables dsid or vexist, if so this macro
will clash;
dsid= open( &dataset );
if dsid then do;
  vexist=varnum( dsid, &varname );
  dsid=close( dsid );
end;
else
  vexist=0;
%mend;

sample use:
data whatever;
  set fromthat;
  %dsHasVar (trim(libname)||'.'||memname, name);
  if vexist then ...

  %dsexist ('SASUSER.CRIME', 'PUNISH');
  if vexist then ...
run;


"Shawn Ribordy" <pndswimming@hotmail.com> wrote in message
news:3911B1DD.36ADABE3@hotmail.com...
> John,  This macro seems to work great, but I can't figure out how to test
the
> return value.
>
> I tried
> %VAREXIST(TESTDATA, TESTVAR);
> IF &VEXIST NE 0 THEN DO;
>      ETC...
> END;
>
> Please help:
>
> John Iwaniszek wrote:
>
> > see the following.
> >
> > /*      This is a collection of macros that retrieve information about a
> > variety of
> >         variable attributes within a given sas data set.
> >
> >         varexist        Returns 0 if varname does not exist in data set
> > inset,
> >                         >0 otherwise.
> >
> > jri 1/11/98 12:06PM
> > s
> > */
> >
> > %macro varexist( inset, varname );
> >         %local
> >                 vexist
> >                 ;
> >         %let dsid=%sysfunc( open( &inset, i));
> >         %if &dsid %then %do;
> >                 %let vexist=%sysfunc( varnum( &dsid, &varname));
> >                 %let rc=%sysfunc( close( &dsid));
> >         %end;
> >
> >         &vexist
> >
> > %mend varexist;
> >
> > Shawn Ribordy wrote:
> > >
> > > I am trying to write a SAS macro that will output XML in a DATA _NULL_
> > > step.  I want to build the macro so it can handle up to 150 different
> > > variables and corresponding XML tags, but I won't necessarily use all
of
> > > them when I call the macro.  I only want to output the XML tags and
> > > variable if the variable exists.
> > >
> > > Is there a way to test whether or not a variable is in a dataset
without
> > > generating an error?
> > >
> > > IF FCTYNO THEN DO;
> > >     etc....
> > > END;
> >
> > --
> > John Iwaniszek
> >
> > Statistical Programming Manager
> > Stat-Tech Services, LLC
> >
> > 919 571 6444
> >
> > Developers of the Macro Reporting System - Delivering
> > Statistical reports in ASCII, RTF, and HTML
> >
> > http://www.StatTechServices.com
>