/************************************************************
 * Macro Quoting
 * 
 * SAS will mask some special characters in macro variable 
 * in order to treat them as text. Sometimes, we need manually
 * unmask the macro variable to make it work as intended.
 *
 * Peng Zeng (Auburn University)
 * 10-17-2018
 ************************************************************/

/* Turn on SYMBOLGEN to check the results of resolving macro
 * variable references */
options symbolgen;

/* The following SAS shows error
 * Macro variable TESTVAL resolves to 'aaa'
 * ERROR 386-185: Expecting an arithmetic expression.
 */

%let val = aaa;
%let testval = %str(%'&val%');
data _null_;
  val = &testval;
  put 'VAL = ' val;
run;

/* The following SAS is correct 
 * Macro variable TESTVAL resolves to 'aaa'
 */

%let val = aaa;
%let testval = %str(%'&val%');
data _null_;
  val = %unquote(&testval);
  put 'VAL = ' val;
run;


/* The following SAS shows error 
 * Macro variable TESTVAL resolves to aaa
 * Variable aaa is uninitialized
 */

%let val = aaa;
%let testval = %str(&val);
data _null_;
  val = %unquote(&testval);
  put 'VAL = ' val;
run;