topic %Do %while loop in SAS Programming

%Do %while loop

SASAna — Tue, 25 Oct 2016 21:04:54 GMT

Hi SAS users,

Do while loop is going more than it should be in a macro.

sysparm has filenames reading from unix which are tilda(~) delimited. Each File names are of 30 characters.

It is going till 135 loops though i am pssing 2 files for testing.

%MACRO test;

DATA UNIX_FILES;
length MANUAL_FILES $32767;
%LET i=1;

%do %while (&i <= (%length(compress("&sysparm",'~','k')) +1));
%let MANUAL_FILES = %scan("&sysparm",&i,"~");

etc

%let i = %eval(&i+1);
%end;

%MEND;

%test;

Re: %Do %while loop

Astounding — Tue, 25 Oct 2016 21:25:30 GMT

You have more than one error here, related to how macro language executes functions.

The easier error to clean up concerns %SCAN. Macro language does not need quotes around character strings. The double quotes should all be removed. In this case, a lucky accident occurred. The third parameter is telling %SCAN to use both double quotes and tildas as delimiters. So the extra double quotes around &SYSPARM are being treated as delimiters and end up not being harmful.

The crucial error concerns COMPRESS. Macro language does not execute DATA step functions. To macro language, "compress" is just a set of characters. If you want macro language to execute a DATA step function, you have to add %SYSFUNC. It works with most (not all) data step functions. Once you get macro language to execute the function, the quotes must again be removed:

%do %while (&i <= (%length(%SYSFUNC(compress(&sysparm,~,k))) +1));

Re: %Do %while loop

RW9 — Wed, 26 Oct 2016 08:39:27 GMT

You can simply your code:

data unix_files;
  length manual_files $30;
  do i=1 to countw("&sysparm.","~");
    manual_files=scan("&sysparm.",i,"~");
    output;
  end;
run;

If you need to do something, then replace the output step with a call execute() to either generate the code, or call a macro with manual_files as parameter.

Re: %Do %while loop

SASAna — Wed, 26 Oct 2016 14:07:09 GMT

Thank you, worked like charm 🙂