declare (c1, c2) character (1);
declare run_length fixed binary;
declare input file;

open file (input) title ('/RLE.DAT,type(text),recsize(20000)');
on endfile (input) go to epilog;

get file (input) edit (c1) (a(1));
run_length = 1;
do forever;
   get file (input) edit (c2) (a(1));
   if c1 = c2 then
      run_length = run_length + 1;
   else
      do; put edit (trim(run_length), c1) (a); run_length=1; end;
   c1 = c2;
end;
epilog:
   put edit (trim(run_length), c1) (a);
   put skip;


/* The reverse of the above operation: */
declare c character (1);
declare i fixed binary;
declare new file;

open file (new) title ('/NEW.DAT,type(text),recsize(20000)');
on endfile (new) stop;
do forever;
   run_length = 0;
   do forever;
      get file (new) edit (c) (a(1));
      if index('0123456789', c) = 0 then leave;
      run_length = run_length*10 + c;
   end;
   put edit ((c do i = 1 to run_length)) (a);
end;