栈与队列实现

围绕两点，加深对栈与队列的理解
1 如何用两个栈实现一个队列
2 如何用两个队列实现一个栈
栈与队列 C++ 简易实现
  1 typedef int DataType;
  2 //简易栈
  3 class stack
  4 {
  5 private:
  6     enum {size=10};
  7     DataType element[size];
  8     int top; //指向栈顶
  9 public:
 10     stack():top(0) {}
 11     bool empty() { return top == 0; }
 12     bool full() { return top == size; }
 13     bool push (const DataType data);
 14     const DataType & pop();
 15 };
 16 bool stack::push (const DataType data)
 17 {
 18     if (full())
 19     {
 20         return false;
 21     }
 22     element[top++] = data;
 23     return true;
 24 }
 25 const DataType & stack::pop()
 26 {
 27     if (empty())
 28     {
 29         return -1;
 30     }
 31     return    element[--top];    
 32 }
 33 //简易队列
 34 class Queue
 35 {
 36 private:
 37     struct Node
 38     {
 39         DataType data;
 40         Node * next;
 41     };
 42     Node * front; //队头
 43     Node * rear;  //队尾
 44     int length;
 45     const int qsize;
 46     Queue(const Queue & q):qsize(0) {}  //防止滥用拷贝，与赋值
 47     Queue & operator=(const Queue & q) { return *this; }
 48 public:
 49     Queue(int qs);
 50     ~Queue();
 51     bool empty()const        { return front == rear;}
 52     bool full()const        { return length == qsize;}
 53     int getlength()const    { return length;}
 54     bool enqueue(const DataType &data);
 55     bool dequeue();
 56 };
 57 Queue::Queue(int qs):qsize(qs),length(0)
 58 {
 59     front = new Node;
 60     front->next = NULL;
 61     rear = front;
 62 }
 63 Queue::~Queue()
 64 {
 65     for (Node *p = front; p != NULL; )
 66     {
 67         Node *pTemp = p->next;
 68         delete p;
 69         p = pTemp;
 70     }
 71     front = rear = NULL;
 72 }
 73 bool Queue::enqueue(const DataType &data)
 74 {
 75     if (full())
 76     {
 77         return false;
 78     }
 79     Node *p = new Node;
 80     p->data = data;
 81     p->next = NULL;
 82     rear->next = p;
 83     rear = p;
 84     ++length;
 85     return true;
 86 }
 87 bool Queue::dequeue()
 88 {
 89     if (empty())
 90     {
 91         return false;
 92     }
 93     Node *p = front->next->next;
 94     delete front->next;
 95     front->next = p;
 96     if (p == NULL)
 97     {
 98         rear = front;
 99     }
100     --length;
101     return true;
102 }