Deleting User-Defined Macro Variables from the Global Symbol Table

You can now use the %SYMDEL macro function to delete user-defined macro variables from the global symbol table.

Note: The %SYMDEL function works only on GLOBAL macro variables.

This is important if your global variables are updated at any point e.g. in a loop. If you need to delete all user-defined macro variables from the global symbol table, then use the following macro. In the example below you will see that a macro variable called mymac1 is set a value of 'Dave'. Once this macro variable has been set, the macro delvars which uses the %symdel function is called. This immediately removes all user-defined global macro variables. To test that the global macro variable &mymac1 has been deleted we've used a %put statement which generates the error.

WARNING: Apparent symbolic reference MYMAC1 not resolved, which proves the macro variable no longer exists.

%let mymac1=Dave;
%put &mymac1;
%macro delvars;
      data vars;
          set sashelp.vmacro;
      run;
      data _null_;
          set vars;
          if scope='GLOBAL' then
              call execute('%symdel '||trim(left(name))||';');
      run;
%mend;
%delvars
%put &mymac1;

NB : This code will run correctly from SAS 8.2 onwards and has been tested on Windows, Unix and the OS/390 operating systems

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