%IF condition returning FALSE for date condition which should return TRUE

[bjlav90]

Hi All,

I have a macro variable like below which is triggered in my first program.

%let ddmmyyyy = "28Feb2019"d;	

On another program inside a macro i have a simple IF statement, see below:

%if &ddmmyyyy. >= '31DEC2018'd %then %do;

I expect this to return a TRUE value however when i run the macro, the IF statement returns FALSE. See below for the extract from the LOG. 

MLOGIC(My_Macro): Beginning execution.
SYMBOLGEN: Macro variable DDMMYYYY resolves to "28Feb2019"d
MLOGIC(My_Macro): %IF condition &ddmmyyyy. >= '31DEC2018'd is FALSE
MLOGIC(My_Macro): Ending execution.

It seems to return false if the days are less than 31 as it runs as expected for 31/12 and 31/01. Does anyone know why this is happening? I have a solution in place but would like to understand why this is happening.

Thanks

Using SAS EG, version 9.2

[Astounding · Accepted solution]

Macro language does not resolve dates into numeric values on SAS's date scale.  It makes comparisons based on the characters it finds, just as if you asked:

%if abc > xyz %then ....;

If you want to tell macro language to convert the date values to numeric dates, apply %sysevalf:

%if %sysevalf(&ddmmyyyy >= '31DEC2018'd) %then %do;

[PaigeMiller]

You can't do this with macro variables. Macro variables are simply considered text, they have no other meaning — and are not interpreted as actual dates. So the test you are doing in the %IF is testing to see if the text string is greater than the other text string, and it is not greater, thus you get FALSE.

You could use something like this:

%if %sysevalf(&ddmmyyyy. >= '31DEC2018'd) %then ...

[bjlav90]

Thanks a lot @Astounding and @PaigeMiller. Makes sense.