It is probably a lot easy to play with getting the date and datetime value in a data step. You can then use CALL SYMPUTX() to generate your macro variables.
data _null_;
end=today();
start=end-45 ;
end_dt=dhms(end,0,0,0);
start_dt=dhms(start,0,0,0);
put (start end) (= yymmdd10.) (start_dt end_dt) (= datetime19.);
call symputx('startdate',quote(put(start,yymmdd10.),"'"));
call symputx('enddate',quote(put(end,yymmdd10.),"'"));
call symputx('start_dt',quote(cats(put(start_dt,datetime19.)))||'dt');
call symputx('end_dt',quote(cats(put(end_dt,datetime19.)))||'dt');
run;
Results:
start=2018-10-03 end=2018-11-17 start_dt=03OCT2018:00:00:00 end_dt=17NOV2018:00:00:00
555 %put &=startdate;
STARTDATE='2018-10-03'
556 %put &=enddate;
ENDDATE='2018-11-17'
557 %put &=start_dt;
START_DT="03OCT2018:00:00:00"dt
558 %put &=end_dt;
END_DT="17NOV2018:00:00:00"dt
Note that if you are going to use those date or datetime values in SAS code then there is no need to format them in human friendly ways. You can just use the underlying integer values.
call symputx('startdate_easy',start);
call symputx('enddate_easy',end);
call symputx('start_dt_easy',start_dt);
call symputx('end_dt_easy',end_dt);
560 %put &=startdate_easy;
STARTDATE_EASY=21460
561 %put &=enddate_easy;
ENDDATE_EASY=21505
562 %put &=start_dt_easy ;
START_DT_EASY=1854144000
563 %put &=end_dt_easy ;
END_DT_EASY=1858032000