stacklink

program StackList;

type
  TpStackElement = ^TStackElement;
  TStackElement = record
    info : integer;
    previous : TpStackElement;
  end;

var
  pStackPointer : TpStackElement;
  pTemp : ^TStackElement;
  answer : char;
  element : integer;

procedure push(pushMethodElement : integer);
begin
  new(pTemp);
  pTemp^.info := pushMethodElement;
  pTemp^.previous := pStackPointer;
  pStackPointer := pTemp;
end;

procedure pop();
begin
  if (pTemp <> nil) then
  begin
    pTemp := pStackPointer;
    //dispose(pStackPointer);
    pStackPointer := pStackPointer^.previous;
    dispose(pTemp);
  end;
end;

procedure output();
begin
  pTemp := pStackPointer;
  while (pTemp <> nil) do
  begin
    write(pTemp^.info, ' ');
    pTemp := pTemp^.previous;
  end;
end;

begin
  pStackPointer := nil;

  repeat

    writeln('1. Add element');
    writeln('2. Remove element');
    writeln('3. Output');
    writeln('4. Dispose');
    readln(answer);
    case answer of
    '1':
      begin
        write('Enter the new element to add: ');
        readln(element);
        push(element);
      end;
    '2':
      begin
        pop();
        writeln;
      end;
    '3':
      begin
        writeln;
        output();
        writeln;
      end;
    '4': dispose(pStackPointer);
    end;
    //writeln(pTemp^.info);

  until (answer = 'n');

end.