march %let age2=%str(if age < 35 then group = "<35"; else group = "35+";); data test; input age @@; &age2; datalines; 19 50 10 34 44 30 ; run; proc print data=test; var &age2; run; 提示说没有if变量;在if前加%说不允许open code。请问怎么改?谢谢!