topic Comparison between numbers in macro in SAS Programming

Comparison between numbers in macro

gabonzo — Mon, 25 Jan 2021 20:56:22 GMT

Here's something interesting:

%macro test(a);
	
	%if &a. >= 0 %then %put LARGER;
	%else %put SMALLER;

%mend;

%test(.75);
MLOGIC(TEST): Beginning execution.
MLOGIC(TEST): Parameter A has value .75
SYMBOLGEN: Macro variable A resolves to .75
MLOGIC(TEST): %IF condition &a. >= 0 is FALSE
MLOGIC(TEST): %PUT SMALLER
SMALLER

%test(0.75);
MLOGIC(TEST): Beginning execution.
MLOGIC(TEST): Parameter A has value 0.75
SYMBOLGEN: Macro variable A resolves to 0.75
MLOGIC(TEST): %IF condition &a. >= 0 is TRUE
MLOGIC(TEST): %PUT LARGER
LARGER

How can this happen in a software that is supposedly world leader in statistics and data analysis, and whose license costs thousands of dollars? HOW?

Re: Comparison between numbers in macro

FreelanceReinh — Mon, 25 Jan 2021 21:29:02 GMT

Hi @gabonzo,

Since SAS software does have all these positive attributes, you can be (almost) sure that this behavior of the SAS macro language is not a bug, but that it is intended and well documented. Here: How the Macro Processor Evaluates Arithmetic Expressions and How the Macro Processor Evaluates Logical Expressions.

So, if you want to feed non-integers to a macro like this, use the %SYSEVALF function in the %IF condition:

%if %sysevalf(&a. >= 0) %then ...

Re: Comparison between numbers in macro

gabonzo — Mon, 25 Jan 2021 21:21:22 GMT

Great! Maybe they should spend less money in documentation and more in useful stuff, like, I don't know, native functions?