topic Re: Test if a macro variable has missing value in SAS Programming

Test if a macro variable has missing value

UdayGuntupalli — Wed, 10 Apr 2019 23:17:57 GMT

All,
I have a simple question. How can one perform a logical test to validate if a macro variable has missing value ?

For e.g.:

%Let a = .; 
%Put &a.; 
%If &a = %str() %Then 
%Do;
%Put "1";
%End;

I thought something like this, but doesn't get me too far.

Re: Test if a macro variable has missing value

Astounding — Thu, 11 Apr 2019 00:04:48 GMT

There are several ways, and an entire paper has been published on the subject. My favorite way:

%if %length(&a) %then %do;

Re: Test if a macro variable has missing value

Astounding — Thu, 11 Apr 2019 00:06:50 GMT

That's for a nonnull value. For a null value:

%if %length(&a)=0 %then %do;

Re: Test if a macro variable has missing value

UdayGuntupalli — Thu, 11 Apr 2019 01:26:23 GMT

@Astounding ,
Thank you for your response. May I ask you to offer a little more clarity ,

%Let a = . ;
%if %length(&a) %then 
	%do;
		%put 1; 
	%end;
	%else;
		%put 0; 
	%end;

This returns an error. Can you point as to what is wrong ? Additionally, can you point me to the paper you are referring to ?

Re: Test if a macro variable has missing value

Astounding — Thu, 11 Apr 2019 01:33:51 GMT

In macro language . is a character and not a missing value.

This statement is incorrect:

%else;

It should be:

%else %do;

Authors of the paper are Chung and King. For me, it's too difficult to find and post links using a mobile phone.

Re: Test if a macro variable has missing value

Ksharp — Thu, 11 Apr 2019 13:37:13 GMT

%If &a =  %Then %Do;%Put "1";%End;

Re: Test if a macro variable has missing value

FreelanceReinh — Tue, 16 Apr 2019 16:43:14 GMT

@UdayGuntupalli wrote:
(...) Additionally, can you point me to the paper you are referring to ?

Just for completeness, this is (most likely) the paper Astounding referred to: https://support.sas.com/resources/papers/proceedings09/022-2009.pdf