Hi! I have a dataset where each row is a different person and each column is the date that they visited the study site. I have list of variables: Pdate1-Pdate1360 and Qdate1-Qdate705. I want to create a flag variable called Flagvar that indicates whether any of the Q dates fell within 30 days of any of the Pdates, but I’m new to arrays and not sure where I’m going wrong. Since I already have over 2000 columns I don't want to create a cartesian product. Here is my code: data want; set have;       array Pdate{1360} Pdate1-Pdate1360;       array Qdate{705} Qdate1-Qdate705;             do k=1 to 1360;             do j=1 to 705;             if intck('day', Pdate{k}, Qdate{j}) le 30                   then Flagvar=1;                   else Flagvar=0;             end;       end; run;   Suggestions, please? Thanks in advance! I'm using SAS 9.4. ... View more