For the last part of your code, I have modified it to macro, hopefully it is what you want: %macro test; data _d_;   %do i = 1 %to &mthcount;    runmth = "&&mth&i";    output;    %a(&&mth&i,&i);   %end;    run;    %mend;    %test    proc print;run; Kindly Regards, Haikuo ... View more

Mike, I can be aware of two problems in your code: 1. Using %do %while (&var_name ne); when 'var_name' is not available until next step. %do %while evaluates expression at the top of the loop, instead, %do %until evaluates on the bottom. 2. Misused %scan(). "" should be removed from  %scan(&varlist,&i,""); So the working code looks like: %let varlist=yy zz aa; %MACRO test(varlist=); %let i=1; %do %until (&var_name eq); %let var_name=%scan(&varlist,&i); %put &var_name; %let i=%eval(&i+1); %end; %mend; %test(varlist=&varlist) As an alternative, you can also try: %MACRO test(varlist=); %do i=1 %to %sysfunc(countw(&varlist)); %let var_name&i=%scan(&varlist,&i); %put &&var_name&i; %end; %mend; Kindly Regards, Haikuo ... View more

Something like this may get your started: data have; infile cards; format bill_end_date date9.        bill_st_date date9.; input id bill_end_date : date9.; bill_st_date=intnx('mon', bill_end_date,-1,'sameday'); cards; 1 12Jan2011 2 23Feb2011 ; proc print;run; Kindly Regards, Haikuo ... View more