Help to understand code

[woo]

Hello friends, please help me to understand this code, this is not my code, its existing code 

I am testing code where one dataset "test" resolving with 3 observation 

date            file_name 

20Jan16     test_file_20160120.txt

19Jan16     test_file_20160119.txt

18Jan16     test_file_20160118.txt

Now after this dataset (test) created, below code is running and its giving only 1 observation, i really don't know why it is resolving to one but i am expecting it should has 3 observation 

%macro test (x_date);

%let store_x_date="null";

data test_2;

retain stop_ind;
if _N_ = 1 then stop_ind = 0;
set test;
by DESCENDING DATE;
if last.DATE = 1 then do;
if stop_ind = 0 then do;
output;
Author_DATE = put(DATE, date.);
call symput("&x_date.",Author_DATE);
end;
stop_ind = 1;
end;
if stop_ind = 0 then output;
run;

%mend;

%test (store_x_date);

Thank you

[Reeza]

This is where formatting your code helps.  Note that there's an output statement nested in an IF condition and a second one in the last statement. The goal seems to be to create a macro variable.

%macro test (x_date);

%let store_x_date="null";

  data test_2;
  retain stop_ind;
  
  if _N_ = 1 then stop_ind = 0;

  set test;
  by DESCENDING DATE;

  if last.DATE = 1 then do;
        if stop_ind = 0 then do;
              output;
              Author_DATE = put(DATE, date.);
              call symput("&x_date.",Author_DATE);
        end;
   stop_ind = 1;
   end;

   if stop_ind = 0 then output;
   run;
%mend;

%test (store_x_date);

[Astounding · Accepted solution]

Some contributing factors:

• Since the DATA step contains an OUTPUT statement, you will only output an observation when an OUTPUT statement executes.
• All OUTPUT statements depend on having STOP_IND=0
• For this particular set of 3 observations, the 1st observation will output and then set STOP_IND=1
• For the 2nd and 2rd observations, STOP_IND=1, so nothing gets output

I hope this is enough ... there's really no substitute for understanding what the statements do.

[woo]

Thanks a lot Astouning and Reeza, appreciate your input,