macro variables

[rawindar]

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

[Peter_C]

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

[Cynthia_sas · Accepted solution]

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

[rawindar]

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

[art297]

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;