SAS Macro Language: Reference

Global Macro Variables

Global Macro Variables illustrates the global symbol table during execution of the following program:

%let county=Clark;

%macro concat;
   data _null_;
      length longname $20;
      longname="&county"||" County";
      put longname;
   run;
%mend concat;

%concat

Calling the macro CONCAT produces the following statements:

data _null_;
      length longname $20;
      longname="Clark"||" County";
      put longname;
run;

The PUT statement writes the following to the SAS log:

Clark County

Global Macro Variables

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Global macro variables include the following:

all automatic macro variables except SYSPBUFF. See Chapter 13, "Macro Language Dictionary," for more information on SYSPBUFF and other automatic macro variables.
macro variables created outside of any macro.
macro variables created in %GLOBAL statements. See "Creating Global Macro Variables" later in this chapter for more information on the %GLOBAL statement.
most macro variables created by the CALL SYMPUT routine. See Special Cases of Scope with the CALL SYMPUT Routine for more information on the CALL SYMPUT routine.

You can create global macro variables any time during a SAS session or job. Except for some automatic macro variables, you can change the values of global macro variables any time during a SAS session or job.

In most cases, once you define a global macro variable, its value is available to you anywhere in the SAS session or job and can be changed anywhere. So, a macro variable referenced inside a macro definition is global if a global macro variable already exists by the same name (assuming the variable is not explicitly defined as local with the %LOCAL statement or in a parameter list). The new macro variable definition simply updates the existing global one. Exceptions that prevent you from referencing the value of a global macro variable are

when a macro variable exists both in the global symbol table and in the local symbol table, you cannot reference the global value from within the macro that contains the local macro variable. In this case, the macro processor finds the local value first and uses it instead of the global value.
if you create a macro variable in the DATA step with the SYMPUT routine, you cannot reference the value with an ampersand until the program reaches a step boundary. See Chapter 4, "Macro Processing," for more information on macro processing and step boundaries.

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