recursion problem - Gpc

22 Jun 2004


      I am getting a recursion problem I don't understand. (gpc-20040516, LINUX on a Pentium 4 laptop.)
This is a (silly) example program (enclosed as a gzipped tar file.):
program subset_problem(input,output);
const setlimit = 4;
type
subset = set of 0..255;
var
seta, setb: subset;
function recursive_setprint(set1: subset):subset;
var
i           : integer;
found       : boolean;
returned    : boolean;
begin
  if set1 <> [] then
    begin
    i:= 0;
    found := false;
    while ((i <= setlimit) and (not found)) do
      begin
      if i in set1 then
        begin
        writeln('first element: ',i);
        found := true;
        recursive_setprint := recursive_setprint(set1 - [i]);
        end;
      i := i + 1;
      end
    end
end;
begin
  seta := [0..setlimit];
  setb :=  recursive_setprint(seta);
end.
I'm getting the following output:
first element: 0
first element: 1
first element: 2
first element: 3
first element: 4
first element: 4
first element: 3
first element: 4
first element: 4
first element: 2
first element: 3
first element: 4
first element: 4
first element: 3
first element: 4
first element: 4
first element: 1
first element: 2
first element: 3
first element: 4
first element: 4
first element: 3
first element: 4
first element: 4
first element: 2
first element: 3
first element: 4
first element: 4
first element: 3
... and so on.
I'm expecting:
first element: 0
first element: 1
first element: 2
first element: 3
first element: 4
(This is the output I am getting with Digital Pascal.)
Thanks for your help with this.