Example 1: Creating a Function and Calling the Function from a DATA Step

proc fcmp outlib=sasuser.funcs.trial;

   function study_day(intervention_date, event_date);

      n = event_date - intervention_date;
         if n >= 0 then
            n = n + 1;
         return (n);
   endsub;

options cmplib=sasuser.funcs;

data _null_;
   start = '15Feb2008'd;
   today = '27Mar2008'd;
   sd = study_day(start, today);

   put sd=;
 

run;