topic Trouble comparing date macros in a macro in SAS Programming

Trouble comparing date macros in a macro

python_user — Thu, 06 Jan 2022 17:59:59 GMT

I can't figure out what I'm doing wrong:

%macro test();

%if "06DEC2021"d<"05JAN2022"d
%then %do;
%put "Lesser";
%end;
%else %do;
%put "Why doesn't it work?";
%end;
%mend;

%test();

How are you supposed to compare dates?

Thanks

Re: Trouble comparing date macros in a macro

PaigeMiller — Thu, 06 Jan 2022 18:12:54 GMT

The macro processor does not recognize dates as dates, it recognizes them as text strings. And text strings sort alphabetically, so 05JAN2022 is less than (alphabetically) 06DEC2021.

To compare dates, use either a SAS data step, or convert the dates to SAS date values which are integers which can then be compared by the SAS macro processor effectively.

data example;
     length value $ 7;
     if '06DEC2021'd < '05JAN2022'd then value='Lesser';
     else value='Greater';
run;

%let abc=%sysevalf("05JAN2022"d);
%let def=%sysevalf("06DEC2021"d);
%if &abc<&def %then %do; %put LESSER; %end;
%else %do; %put GREATER; %end;

Re: Trouble comparing date macros in a macro

python_user — Thu, 06 Jan 2022 18:19:34 GMT

Hi @PaigeMiller ,

Thanks, I guess it explains why it's not working. Unfortunately for me the sysevalf also does not work (output is GREATER):

%macro test();
%let abc=%sysevalf("05JAN2022"d);
%let def=%sysevalf("06DEC2021"d);
%if &abc<&def %then %do; %put LESSER; %end;
%else %do; %put GREATER; %end;
%mend;

%test();

any other ideas on how to compare dates in a macro?

Re: Trouble comparing date macros in a macro

PaigeMiller — Thu, 06 Jan 2022 18:22:32 GMT

@python_user

GREATER is the correct answer, at least on my calendar.

Re: Trouble comparing date macros in a macro

python_user — Thu, 06 Jan 2022 18:29:35 GMT

Ha! So it is. Apologies and thanks again.

Re: Trouble comparing date macros in a macro

ballardw — Thu, 06 Jan 2022 18:31:09 GMT

@python_user wrote:

Hi @PaigeMiller ,

Thanks, I guess it explains why it's not working. Unfortunately for me the sysevalf also does not work (output is GREATER):

%macro test();
%let abc=%sysevalf("05JAN2022"d);
%let def=%sysevalf("06DEC2021"d);
%if &abc<&def %then %do; %put LESSER; %end;
%else %do; %put GREATER; %end;
%mend;

%test();

any other ideas on how to compare dates in a macro?

Look back at the direction of the comparison and your values. "05JAN2022"d is greater than (after) "06DEC2021"d .

Run the macro with options Symbolgen and MLOGIC

options  symbolgen mlogic;
%test();
options  nosymbolgen nomlogic;

123  options  symbolgen mlogic;
124  %test();
MLOGIC(TEST):  Beginning execution.
MLOGIC(TEST):  %LET (variable name is ABC)
MLOGIC(TEST):  %LET (variable name is DEF)
SYMBOLGEN:  Macro variable ABC resolves to 22650
SYMBOLGEN:  Macro variable DEF resolves to 22620
MLOGIC(TEST):  %IF condition &abc<&def is FALSE
MLOGIC(TEST):  %PUT GREATER
GREATER
MLOGIC(TEST):  Ending execution.
125  options  nosymbolgen nomlogic;

Re: Trouble comparing date macros in a macro

PaigeMiller — Thu, 06 Jan 2022 19:21:19 GMT

Yes, good point @ballardw

Actually looking at the values of your macro variables is always an excellent debugging strategy, and I'm surprised when people don't do that.