*Program 13-1 Converting values of 999 to a SAS missing 
 value - without using arrays;
data new;
   set learn.SPSS;
   if Height = 999 then Height = .;
   if Weight = 999 then Weight = .;
   if Age    = 999 then Age    = .;
run;

*Program 13-2 Converting values of 999 to a SAS missing value
 - using arrays;
data new;
   set learn.SPSS;
   array myvars{3} Height Weight Age;
   do i = 1 to 3;
      if myvars{i} = 999 then myvars{i} = .;
   end;
   drop i;
run;

*Program 13-3 Rewriting Program 13 2 using the CALL MISSING routine;
data new;
   set learn.SPSS;
   array myvars{3} Height Weight Age;
   do i = 1 to 3;
      if myvars{i} = 999 then call missing(myvars{i});
   end;
   drop i;
run;