因为Phonenumber是数值变量

因為 phonenumber 以 best12. 型式由 numeric 轉為character , 所以 有2個leading spaces.

你可以用!!也可以用||。兩個沒什么區別的

是不是所有数值变量在data步赋值时都自动是best12.的格式？

是不是所有数值变量在data步赋值时都自动是best12.的格式？

An automatic data conversion is performed whenever a numeric variable is used where
SAS expects a character value. The numeric variable is written with the BEST12. format
and the resulting character value is right-aligned when the conversion occurs. In this
example, the value of Phonenumberis converted to character and right-aligned before the
SUBSTR function is performed. Since there are only 10 digits in the value of
Phonenumber, the right-aligned value begins with two blanks. Therefore the SUBSTR
function picks up two blanks and a 3, and uses the BEST12. format to assign that value to
Code. Then, the parentheses are concatenated before and after the two blanks and a 3.

可是！！是什么意思啊？而且为什么（）里只有3位？

多谢(o^^o)

1 )双感叹号 !! 是字符串连接符, 和 ||  的作用是一样的.
   此处是把括号与substr计算的结果连接在一起2) substr提取函数,只能从字符变量中提取,如果原来为数值变量,则调用该函数时自动将数值变量转为字符变量,不过按best12.格式转换.