topic difference between Statment GOTO and %GOTO in SAS Programming

difference between Statment GOTO and %GOTO

SAS_inquisitive — Mon, 07 Dec 2015 17:52:46 GMT

I was running the following code given in the sas documentation.

data info;   
   input x;
   if 1<=x<=5 then go to add;
   put x=;
   add: sumx+x;
   datalines;
7
6
323
;

I think " if condition is false", why it is executing the statment in the add label.

Whereas in the context of the %goto, it executes %goto label when it is true only (code below- http://www.lexjansen.com/nesug/nesug03/cc/cc016.pdf).

%MACRO READ;

%DO I = 1 %TO 4;

%IF &I = 3 %THEN %GOTO OUT;

DATA CTY_&I;

INFILE "D:\NESUG\CTY_&I";

INPUT ID F96 F97 F98;

RUN;

%OUT: %END;

%MEND READ;

%READ

I am really confused now. I thought %goto was just macro counterpart of goto.

Re: difference between Statment GOTO and %GOTO

ballardw — Mon, 07 Dec 2015 20:23:42 GMT

Your data step example ADD is just a label. Since you do not have any way of not executing it then you get the result everytime. The code below is the same as yours.

data info;   
   input x;
   if 1<=x<=5 then go to add;
   put x=;
   add: 
   sumx+x;
   datalines;
7
6
323
;

If you do not want the sumx+x executed for every step the Return is used with Goto

data info;
   input x;
   if 1<=x<=5 then go to add;
   put x=;
   return;    
      /* SUM statement not executed */
      /* if x<1 or x>5              */
   add: sumx+x;
   datalines;
7
6
323
;

Re: difference between Statment GOTO and %GOTO

SteveM_UK — Tue, 08 Dec 2015 12:00:25 GMT

Hi,

BallardW is correct in the data step code posted and his explanation of the 'return;' statement.

To explain why %GOTO behaved as it did, consider what is after the %IF in your code: it is a complete datastep with a RUN; which terminates that group of SAS statements. In that respect it is similar to "return;" (not strictly true, but close enough). Remember also that macro language is simply a mechanism for generating SAS code - it has its own execution logic that passes the generated code for SAS to compile and execute.

So the effect of your macro conditional is to either generate a whole data step (when the condition is false), or to skip that by jumping to the %END statement, labelled with the name OUT.

BTW, on a coding style point, I recommend *always* having an explicit "else..." along with "if...then..." - too often I've had to debug someone else's code that has misbehaved because the author didn't do that!

Regards

Steve M.