前序非遞迴實現

void pre_show2() {
        if (root == 0)
            return;
        stack<Node<T> * > con;
        Node<T>* t = root;
        con.push(t);
        while (!con.empty()) {
            cout << t->data << " ";
            if (t->right)
                con.push(t->right);
            if
 
 (t->left)
                t = t->left;
            else {
                t = con.top();
                con.pop();
            }
        }
        cout << endl;
    }

中序非遞迴實現

void in_show2()
    {
        if (root == 0 )
            return;
        stack<Node<T>*> q;
        Node<T>* p = root;
        while
 
 (!q.empty() || p) {
            if (p)
            {   q.push(p);
                p = p->left;
            } else {
                p = q.top();
                q.pop();
                cout << p->data << " ";
                p = p->right;
            }
        }
        cout << endl;
    }
 

後序非遞迴實現

void post_show2() {
        if (root == 0)
            return;
        stack<Node<T>*> q;
        Node<T>* t = root;
        Node<T>* last_visit = 0;
        while (t) {
            q.push(t);
            t = t->left;
        }
        while (!q.empty()) {
            t  = q.top(); q.pop();
            if (t->right == 0 || last_visit == t->right)
            {   //如果是葉子或者一個節點的右孩子已經訪問過了輸出該節點的data值
                cout << t -> data << " ";
                last_visit = t;
            } else {
                q.push(t);
                t = t->right;       //進入右孩子
                while(t){
                    q.push(t);
                    t = t->left;
                }
            }
        }
        cout <<endl;
    }