linusx 发表于 2014-12-23 20:24 http://analytics.ncsu.edu/sesug/2007/HW07.pdf
谢谢 我好好看一下 然后再来理解里所说的意思.....
看了你给的链接 按照原文中的例子 If the first character is an "R"(for "Regional") , we process the remainder of the record. If the first character is anything esle , we will invoke an INPUT statement that has no variables assocated with it.
This null input statemtn has the sole prupose of freeing the line pointer. (In our example , the RUN statement would have released the hold automatically; however, personal preference is to explicitly code the statement in all instances.)