栈和队列5--不带头指针的循环队列

#include<iostream>
#define//循环队列最大长度
using namespace std;

typedef  int elem;//数据类型
typedef struct QNode {
  elem data;
  struct QNode *next;
}*QueuePtr;
typedef struct  {
  QueuePtr rear;//队尾
} LinkQueue;

bool init(LinkQueue &L) {
  L.rear->next= L.rear=new QNode;//头=尾
  return true;
}

//置空序列
bool initQueue(LinkQueue &l) {
  l.rear = l.rear->next;
  QueuePtr temp;
  while (l.rear != l.rear->next) {
    temp = l.rear->next;
    l.rear->next = temp->next;
    delete temp;
  }
  return true;
}

bool isEmpty(LinkQueue l) {
  return l.rear->next->next == l.rear->next;
  //判断头结点的后一个结点==头结点
}

bool push(LinkQueue &l, elem e) {
  QueuePtr temp=new QNode;
  temp->data = e;
  temp->next = l.rear->next;
  l.rear->next = temp;
  l.rear = temp;
  return true;
}

bool dequeue(LinkQueue &l,elem &e) {
  if (isEmpty(l)) return false;
  QueuePtr temp = l.rear->next->next;//头结点后的第一个元素结点"首元结点"
  e = temp->data;
  if (temp == l.rear) {    //队尾只剩下1个点
    l.rear = l.rear->next;  //尾指针指向头结点
    l.rear->next = temp->next;//头指向头
  }
  else
    l.rear->next->next = temp->next;
    //头的后一个指针指向原来的第二个结点的位置
    delete temp;
    return true;
}

bool show(LinkQueue l) {
  elem e;
  if (isEmpty(l)) return false;
  cout << "ShowTime" << endl;
  QueuePtr temp = l.rear->next->next; //头结点后的第一个元素结点"首元结点"
  while (temp!=l.rear->next) {
    e = temp->data;
    cout << e << " ";
    temp = temp->next;
  }
  return true;
}

int main() {
  LinkQueue S; elem e;
  if (init(S))  cout << "init Succeed" << endl;
  else cout << " init Failed" << endl;
  //入栈
  cout << "input e:\t";
  while (cin >> e) {//按"ctrl+z"结束输入
    push(S, e);
    cout << "input e:\t";
  }
  show(S);
  //出栈
  if (dequeue(S, e))
    cout << "移除的头元素是" << e << endl;
  else cout << "栈空" << endl;
  cout << "栈剩下所有元素为" << endl;
  show(S);
  initQueue(S);
  cout << "置空，栈剩下所有元素为" << endl;
  show(S);
}