SAS %eval() Function – Evaluate Expressions in SAS Macro

When working in the SAS Macro Language, you can use the %eval() function to evaluate logical expressions and perform integer arithmetic.

%let a = 3+5;
%let b = 10/5;
%let c = 10>3;
%let eval_a = %eval(&a);
%let eval_b = %eval(&b);
%let eval_c = %eval(&c);

%put &eval_a;
%put &eval_b;
%put &eval_c;

/* Output */
8
2
1

The SAS Macro Language allows us to create dynamic and powerful code which allows us to handle complicated code requirements.

One useful function from the SAS Macro Language is %eval().

When working in the SAS Macro Language, you can use the %eval() function to evaluate logical expressions and perform integer arithmetic.

Macro variables are strings, and so if you have a string which represents an expression, %eval() can help you get the value of that evaluated expression.

Below are some examples of how you can use the %eval() function in SAS to evaluate different expressions.

%let a = 3+5;
%let b = 10/5;
%let c = 10>3;
%let eval_a = %eval(&a);
%let eval_b = %eval(&b);
%let eval_c = %eval(&c);

%put &eval_a;
%put &eval_b;
%put &eval_c;

/* Output */
8
2
1

Using %eval() to Increment a Counter in a SAS Macro

One useful example of using the SAS Macro %eval() function is if you are using a loop and want to increment a counter.

If you are using a do loop in a SAS Macro, or just need to increment a SAS macro variable, you can use %eval().

Below is an example of a do loop in a SAS Macro where we use %eval() to increment a counter variable.

%let counter = 0;

%macro loop_example();
    %do i = 0 %to 3;
        %put &counter;
        %let counter = %eval(&counter+1);
    %end;
%mend;

%loop_example();

/* Output */
0
1
2
3

Hopefully this article has been useful for you to learn how to use the SAS eval() function in the SAS Macro Language.