topic macro variables in SAS Programming

macro variables

rawindar — Sat, 28 Apr 2012 14:24:38 GMT

Hi all,

Can any body help me to understand how it will executes

%let one=two;
%let two=three;
%let three=Check;

%put &one;
%put &&one;
%put &&&one;
%put &&&&one;
%put &&&&&one;
%put &&&&&&one;
%put &&&&&&&one;
%put &&&&&&&&one;
%put &&&&&&&&&one;
%put &&&&&&&&&&one;

what is the differnce between &,&& and &&&

How can i understand this concept.

Thanks &Regards

Rawindarreddy

Re: macro variables

Peter_C — Sat, 28 Apr 2012 15:08:38 GMT

the macro manual is available on-line at http://support.sas.com/documentation

Re: macro variables

Cynthia_sas — Sat, 28 Apr 2012 15:18:42 GMT

In addition to Peter's (excellent) suggestion, searching on the forum would reveal this previous forum posting:

https://communities.sas.com/message/12344#12344 that discusses the forward scan rule and the rescan rule of macro variables (which are the topics you should search for in the documentation). In addition, turning on the system option SYMBOLGEN will help you see the trace of macro variable resolution (including how multiple ampersands are resolved) in the SAS Log. Also, there have been some user group papers on how to approach the resolution of multiple ampersands, such as these two -- there are more if you search:

http://www2.sas.com/proceedings/sugi29/063-29.pdf

http://www2.sas.com/proceedings/sugi22/CODERS/PAPER77.PDF

Also, for a beginner's introduction to macro processing in general, I recommend this paper:

http://www2.sas.com/proceedings/sugi28/056-28.pdf

cynthia

Re: macro variables

art297 — Sat, 28 Apr 2012 22:35:36 GMT

And, after you've read everything that Peter and Cynthia suggested, try running the following expanded version of your code and see if you can predict what the various resulting values will be:

%let Check=four;

%let one=two;

%let two=three;

%let three=Check;

%let four=five;

%let five=six;

%put &one;

%put &&one;

%put &&&one;

%put &&&&one;

%put &&&&&one;

%put &&&&&&one;

%put &&&&&&&one;

%put &&&&&&&&one;

%put &&&&&&&&&one;

%put &&&&&&&&&&one;

%put &&&&&&&&&&&one;

%put &&&&&&&&&&&&one;

%put &&&&&&&&&&&&&one;

%put &&&&&&&&&&&&&&one;

%put &&&&&&&&&&&&&&&one;

Re: macro variables

rawindar — Sun, 29 Apr 2012 03:25:43 GMT

thank......u Cynthia.I got it