代码如下:

#include <iostream>
using namespace std;typedef int ElemType;typedef struct QNode
{ElemType data;QNode *next;
}QNode ,*QueuePtr;typedef struct
{QueuePtr front;QueuePtr rear;
}LinkQueue;bool initQueue(LinkQueue &q)
{q.front = q.rear = new QNode;if (!q.front) return false;q.front->next = nullptr;return true;
}bool destroy(LinkQueue &q)
{while (q.front){q.rear = q.front->next;delete q.front;q.front = q.rear;}q.front = q.rear = nullptr;return true;
}bool clearQueue(LinkQueue &q)
{QNode *p = q.front->next;QNode *s = nullptr;while (p){s = p;p = p->next;delete s;}q.rear = q.front;return true;
}bool queueEmpty(LinkQueue q)
{if (q.front == q.rear) return true;return false;
}int queueLength(LinkQueue q)
{int j = 0;QNode *p = q.front->next;while (p){j++;p = p->next;}return j;
}bool getHead(LinkQueue q, ElemType &e)
{if (q.front == q.rear) return false;e = q.front->next->data;return true;
}bool enQueue(LinkQueue &q, ElemType e)
{QNode *p = new QNode;if (!p) return false;p->data = e;p->next = nullptr;q.rear->next = p;q.rear = p;return true;
}bool deQueue(LinkQueue &q, ElemType &e)
{if (q.front == q.rear) return false;QNode *p = q.front->next;q.front->next = p->next;if (q.rear == p)q.rear = q.front;delete p;return true;
}void vis(ElemType e)
{cout << e << " ";
}void queueTraverse(LinkQueue q, void(*visit)(ElemType))
{QNode *p = q.front->next;while (p){visit(p->data);p = p->next;}
}int main() {LinkQueue q;initQueue(q);int n;int a;cin >> n;for (int i = 0; i < n; i++){cin >> a;enQueue(q, a);}queueTraverse(q, vis);cout << endl;deQueue(q, a);deQueue(q, a);queueTraverse(q, vis);cout << endl;cout << queueLength(q) << endl;return 0;
}