标题: 一个Macro问题 [打印本页] 作者: shiyiming 时间: 2011-1-12 19:57 标题: 一个Macro问题 The following SAS program is submitted:
%let a = cat;
%macro animal(a = frog);
%let a = bird;
%mend;
%animal(a = pig)
%put a is &a;
What is written to the SAS log?
请回答并解释作者: shiyiming 时间: 2012-7-13 21:51 标题: Re: 一个Macro问题 The local symbol table is deleted when the macro finishes execution.That is,the local symbol table exists only while the macro executes.
在这个宏定义中产生的A的值是存在于symbol表中的，而后面的引用是在global表中产生的A值，故其值为cat