topic Re: multiple operators in %if macro in SAS Programming

multiple operators in %if macro

Alexx_ — Wed, 15 Mar 2023 03:19:19 GMT

Hi there,

I am learning a macro program. I am confused about multiple operators. I don't know how SAS evaluates %if comparisons with two operators, one is "(&brand. = Flase)", the other is ">=.". the result of this program returned "Brand is General Electric". may I know why? how to decompose multiple operators?

%macro corpare_brand(brand);
%if ((&brand. = Flase) >=. ) %then %put Brand is General Electric;
%else %put Brand is &brand;
%mend;
%corpare_brand(Coke)

thanks!

Re: multiple operators in %if macro

SASKiwi — Wed, 15 Mar 2023 03:33:19 GMT

If you are just testing equality this works:

%macro corpare_brand(brand);
%if &brand. = Flase %then %put Brand is General Electric;
%else %put Brand is &brand;
%mend;
%corpare_brand(Coke);

Re: multiple operators in %if macro

Alexx_ — Wed, 15 Mar 2023 03:40:31 GMT

yes, I know that works. but "%if &brand. = Flase" returned "Brand is Coke". But I want to know why "%if ((&brand. = Flase) >=. )" returned "Brand is General Electric"

Re: multiple operators in %if macro

Alexx_ — Wed, 15 Mar 2023 03:44:41 GMT

the original macro program showed below:

%macro compare_brand(brand);
%if &brand = GE %then %put Brand is General Electric;
%else %put Brand is &brand;
%mend;
%compare_brand(Coke)

Re: multiple operators in %if macro

SASKiwi — Wed, 15 Mar 2023 03:53:21 GMT

What are you trying to do with this -"%if ((&brand. = Flase) >=. )" ? Some sort of Boolean comparison?

Re: multiple operators in %if macro

Tom — Wed, 15 Mar 2023 04:34:08 GMT

SAS uses %EVAL() to evaluate the condition in a %IF statement.

So just ask %EVAL() what it thinks of those tests.

1009  %put %eval( Coke = Flase );
0
1010  %put %eval(0 >= .);
1

the test:

%if ((&brand. = Flase) >=. ) %then

Is always TRUE.

Do you see why?

The result of a boolean expression is either TRUE (1) or FALSE (0).

If %EVAL() decided to compare them as numbers then both 0 and 1 are larger than a missing value .

And if %EVAL() decided to do a character comparison both '30'x and '31'x are greater than '2E'x.

Re: multiple operators in %if macro

Astounding — Wed, 15 Mar 2023 07:58:23 GMT

This statement doesn't compare anything to the string GE. In macro language, GE means "greater than or equal to".

The easiest workaround would be to add double quotes to the comparison:

%if "&brand" = "GE" %then %put Brand is General Electric;

Re: multiple operators in %if macro

Alexx_ — Wed, 15 Mar 2023 15:58:27 GMT

thanks @Tom