multiple operators in %if macro

[Alexx_]

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!

[SASKiwi]

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);

[Alexx_]

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"

[Alexx_]

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)

[Astounding]

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;

[SASKiwi]

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

[Tom · Accepted solution]

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?

Spoiler

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.

[Alexx_]

thanks @Tom