你顺序都搞错了，应该是：
data test;
input age @@;
if age not in (15,16) then g=1;
else g=2;
cards;
14 15 16 17
;
run;

因为age还未赋值的时候为空值 每读一行结束后 由于没有retain age又会被置为空值
你可以在if前面加一个put age看下age当前的值
也可以加一个retain age看下区别

非常感谢

题目错了吧？ 为何我在70里找不到这个题

61.Consider the data step:
data WORK.TEST;
   infile 'c:\class1.csv' dsd;
   input Name $ Sex $ Age Height Weight;
   if Age NE 16 and Age NE 15 then Group=1;
   else Group=2;
run;
Which statement produces a functionally equivalent result for assigning Group a value?
     A. if Age not in(15,16) then Group=1;  else Group=2;
     B. if (Age NE 16) or (Age NE 15) then Group=1;  else Group=2;
     C. where Age not between 15 and 16 then Group=1; else Group=2;
     D. both A or C will work.