substr(reverse("aa_bb_ccc"）,1,3)

感谢！

data _null_;
A="aa_bb_ccc";
B=substr(reverse(A),1,3);/*倒数第1到3位*/
C=reverse(substr(A,7,3));/*顺数第7-9位*/
put A;
put B;
put C;
run;

运行结果：
aa_bb_ccc
ccc
ccc

这么看reverse这个函数就是倒序的意思吧

我再补充一个
data _null_;
A="aa_bb_ccc";
B=substr(reverse(A),1,3);/*倒数第1到3位*/
C=reverse(substr(A,7,3));/*顺数第7-9位*/
D=substr(A, length(A)-2, 3);/*顺数第5-7位*/
put A;
put B;
put C;
PUT D;
run;

aa_bb_ccc
ccc
ccc
ccc