// 后序遍历非递归   
    public static void PostOrder2(BinTree t) {   
        Stack<BinTree> s = new Stack<BinTree>();   
        Stack<Integer> s2 = new Stack<Integer>();   
        Integer i = new Integer(1);   
        while (t != null || !s.empty()) {   
            while (t != null) {   
                s.push(t);   
                s2.push(new Integer(0));   
                t = t.lchild;   
            }   
            while (!s.empty() && s2.peek().equals(i)) {   
                s2.pop();   
                System.out.print(s.pop().date);   
            }   
  
            if (!s.empty()) {   
                s2.pop();   
                s2.push(new Integer(1));   
                t = s.peek();   
                t = t.rchild;   
            }   
        }   
    }