Your statement tree_ = &trees; is resolving to tree_ = '999', '888', '111', '222', '555', '876', '564', '109','456', '543', '897', '009', '321' ;   similarly hl(i) ne &trees is hl(i) ne '999', '888', '111', '222', '555', '876', '564', '109','456', '543', '897', '009', '321' If you don't know why either of those is an error you need to review a lot of basics before attempting to use macro variables.   I have no idea what you are attempting to do with the tree_ = . If you are attempting to use R like syntax to assign values to the array then that is not going to work.   Using instead of the comparison this: hl(i) not in ( &trees) then  might work if you want to find out that a single value of the array does not appear in the list.   And then tree = whichc('&trees', of hl(*))>0; first has a problem because      whichc('&trees'   resolves to nothing. it uses the literal value &trees because macro variables do not resolve at all inside single quotes. If you used whichc("&trees" then the whichc would be looking for the entire value "'999', '888', '111', '222', '555', '876', '564', '109','456', '543', '897', '009', '321' " to be in a single value of the one of the array elements.   You need to describe exactly what you are attempting to do. Best would be to show code that worked before you added in any macro variables. If you don't have such code, then that is the first thing you need to do.   ... View more

Here's a more complete version.  It assumes your variables are character.  If they are numeric, you would need to switch from SORTC to SORTN. data want (keep=id); set have; array hlth {20}; call sortc (of hlth{*}); do _n_=1 to 19 until (flag=1); if not missing (hlth{_n_}) and hlth{_n_} = hlth{_n_+1} then flag=1; end; if flag=1; run; This version keeps just the ID.  You would have to go back to the original data to check why these IDs are flagged. ... View more