此处用到了scan函数的三个modifier
sas help的说明如下：

a or A

adds alphabetic characters to the list of characters.

d or D  adds digits to the list of characters.

k or Kcauses all characters that are not in the list of characters to be treated as delimiters. That is, if K is specified, then characters that are in the list of characters are kept in the returned value rather than being omitted because they are delimiters. If K is not specified, then all characters that are in the list of characters are treated as delimiters.


为什么上面两个程序得出的结果不一样？