何时引用宏变量

Question

在SAS中，当引用宏变量时，我发现有时候代码在宏引用周围使用双引号，但有些时候它引用不带引号的变量。

什么时候应该在我的&之前使用引号，何时应该不使用引号？

Answer 1

当您使用它们代替通常需要引用的硬编码的非宏文本时，您只需引用宏变量 - 通常在proc或数据步骤代码中，例如，

%let text = Hello; 

/*You need quotes here*/ 
data _null_; 
put "&text"; 
run; 

/*Otherwise you get an error, because SAS thinks hello is a variable name*/ 
data _null_; 
put &text; 
run; 

/*If you already have quotes in your macro var, you don't need to include them again in the data step code*/ 
%let text2 = "Hello"; 
data _null_; 
put &text2; 
run; 

/*In macro statements, everything is already treated as text, so you don't need the quotes*/ 
%put &text; 

/*If you include the quotes anyway, they are counted as part of the text for macro purposes*/ 
%put "&text"; 


/*When you are calling functions via %sysfunc that normally 
require a variable name or a quoted string, you don't need quotes*/ 
%let emptyvar=; 
%put %sysfunc(coalescec(&emptyvar,&text));