Most macro functions are handled by the macro processor before any SAS language statements in the DATA step are executed. For example, the %LET statement and any macro variable references (&macvar) are passed to the macro processor before the program is compiled. In order to create or update macro variables during DATA step execution, you use the SYMPUT routine.

To create a macro variable and assign to it a value that is based on the value of a DATA step variable, you use the SYMPUT routine. In the SYMPUT routine, to assign a literal string as a macro variable name, you enclose the literal in quotation marks. To assign a literal string as a value of the macro variable, you enclose the literal in quotation marks.

The SYMPUT routine enables you to assign a data set variable as the value of a macro variable. You can also use the SYMPUT routine to create a series of related macro variables. Because all macro variable values are character strings, SYMPUT automatically converts any numeric value that you attempt to assign as a value for a macro variable. In an SCL program, you must use SYMPUTN rather than SYMPUT if you are attempting to assign a numeric value to a macro variable.

You can use multiple ampersands to create an indirect reference when the value of one macro variable is the name of another. If you enclose the DATA step variable name in quotation marks in the SYMPUT routine, the new macro variable will have the same name as the DATA step variable rather than having the DATA step variable's value as a name. Use the SYMGET function to obtain the value of a macro variable during the execution of a DATA step.

If more than four consecutive ampersands precede a name token, rescanning continues from left to right until no more triggers can be resolved. The Forward Re-scan rule describes how the macro processor resolves macro variable references that start with multiple ampersands or with multiple percent signs.

A macro variable reference (&macvar) is resolved before any SAS language statements are sent to the compiler. The SYMGET function enables you to obtain the value of a macro variable during the execution of a DATA step or a PROC SQL step. The SYMGET function can also be used to obtain the value of a macro variable during the execution of an SCL program.

To create a macro variable during the execution of a PROC SQL step, use the INTO clause of the SELECT statement. In the INTO clause, you precede the name of the macro variable with a colon.

You can use multiple ampersands to delay the resolution of a macro variable reference. You can also combine macro variable references in order to create new tokens. In this example, the reference &&teach&crs resolves to &teach3 on the first scan. On the next scan, &teach3 resolves to Forest, Mr. Peter.

You can use the SYMGET function in an assignment statement to obtain the current value of a macro variable and to assign that value to a DATA step variable. The SYMGET function enables you to obtain the value of a macro variable during execution of a DATA step, a PROC SQL step, or an SCL program.

The SYMPUT routine can be used in either the DATA step or in an SCL program. In the DATA step, the SYMPUT routine will perform automatic conversion on numeric values that you attempt to assign as values for macro variables, using the BEST12. format. In an SCL program, you should use the SYMPUTN routine if you want to assign a numeric value as a value for a macro variable. In a PROC SQL step, you need to use the INPUT function in order to convert macro variable values to numeric before you compare them to other numeric values.