三种常见生成宏变量方法SAS

/*Three common methods to define user-defined macro variable*/
/*1:the simple approach is to use %let statment*/
/*2:the another one to use call sypmput or call symputx statment in data step*/
/*3:the last one is to use pro sql*/

/*call symputx can strip both leading and trailing blanks while call symput does not trim leading and trailing blanks.*/
/*we can use separated by '' or trimmed to remove blanks.*/

data a;
  x=2;
  y=3;
  z=x+y;
  call symput("z1",z);
  call symputx("z2",z);
run;

%put #&z1.#;
%put #&z2.#;

proc sql noprint;
    select x into : x1 from a;
    select x into : x2 separated by ' ' from a;
    select x into : x3 trimmed from a;
quit;

%put |&x1|;
%put |&x2|;
%put |&x3|;

/*宏会将所有值包含数字在内当做文本值，不能直接计算宏变量，需要使用%eval或者%sysevalf来计算。*/
/*%eval：计算整数值*/
/*%sysevalf：计算浮点数*/

%let a=12;
%let b=11;
%let c=12.3;

%put %eval(&a+&b);
%put %sysevalf(&a+&c);