SAS Macro function conditional on value of Macro Variable

问题

I have a SAS project (EGv7.1) that allows the user to specify a value on the first line. Then, other processes are invoked based on the value specified. One of these is that some other macro variables are assigned. Below is what I have, and it does not seem to be working. I really need the let statement to be first in the sequence, but besides that I am open to changes. Any suggestions?

%let number=8;

%macro my_function();
    %if &number=8 %then 
        %do;
            %let number_text=eight;
            %let number_text_2=equal to eight;
        %end;
    %if &number>8 %then
            %do;
            %let number_text=not eight;
            %let number_text_2=greater then eight;
        %end;
    %if &number<8 %then
            %do;
            %let number_text=not eight;
            %let number_text_2=less than eight;
        %end;
%mend my_function;
%my_function();

%put =================&number==================;
%put ===========The number is &number_text.=============;
%put =======Furthermore, the number is &number_text_2.========;

回答1:

When you use %let statements inside of a macro, the variables default to local scope. That is, they only exist inside the macro. To remedy that add a %global statement inside the macro.

%let number = 8;

%macro my_function();
    %global number_text number_text_2;

    %if %sysevalf(&number = 8) %then 
        %do;
            %let number_text = eight;
            %let number_text_2 = equal to eight;
        %end;
    %else %if %sysevalf(&number > 8) %then
        %do;
            %let number_text = not eight;
            %let number_text_2 = greater than eight;
        %end;
    %else %if %sysevalf(&number < 8) %then
        %do;
            %let number_text = not eight;
            %let number_text_2 = less than eight;
        %end;

%mend my_function;
%my_function();

This tells SAS that the macro variables number_text and number_text_2 should be accessible outside of the macro, which should fix your problem.

I also recommend adding %else to your %ifs. This ensures that each condition is only evaluated if the one preceding it is false. Without %else, each condition is evaluated every time.

As @DomPazz mentioned, it's a good idea to use %sysevalf() when evaluating numeric conditions.

回答2:

If you're not passing in any values why use a macro at all? Here's a way to do it using a data null step.

%let number=3;

data _null_;
if &number=8 then do;
call symputx('number_text_3', "eight", g);
call symputx('number_text_4', "equal to eight", g);
end;
else if &number>8 then do;
call symputx('number_text_3', "not eight", g);
call symputx('number_text_4', "greater than eight", g);
end;
else if &number<8 then do;
call symputx('number_text_3', "not eight", g);
call symputx('number_text_4', "less than eight", g);
end;

run;

%put &number_text_3;
%put &number_text_4;

来源：https://stackoverflow.com/questions/27844703/sas-macro-function-conditional-on-value-of-macro-variable

标签

sas

sas-macro