/* Queue class declarations. */ #ifndef _QUEUE_H_ #define _QUEUE_H_ #include <iostream> using namespace std; typedef char ElemType; typedef struct SNode{ ElemType data; struct SNode* pNext; }Node; class CQueue{ public: CQueue(); bool EnQueue(ElemType elem); // insert an element at rear bool DeQueue(ElemType& elem); // delete an element at front bool isEmpty(); // if queue is empty return true bool Traverse(); // traverse the queue int itsLength(); // get queue's length ~CQueue(); private: Node* rear; // only allow insert operation Node* front; // only allow delete operation }; #endif // _QUEUE_H_

/* class definition. */ #include "queue.h" /* Parameter : none Return : none Description : class default constructor. */ CQueue::CQueue() { front = new Node; rear = front; rear->pNext = NULL; } // default constructor /* Parameter : ElemType Return : true or false Description : insert an element to a queue's rear. */ bool CQueue::EnQueue(ElemType elem) { Node* pNode = new Node; pNode->data = elem; pNode->pNext = NULL; rear->pNext = pNode; rear = pNode; return true; } // EnQueue /* Parameter : ElemType& Return : true or false Description : if queue is not empty, delete the front element. */ bool CQueue::DeQueue(ElemType& elem) { Node* pNode; if (isEmpty()) { return false; } else { pNode = front->pNext; elem = pNode->data; front->pNext = pNode->pNext; return true; } } // DeQueue /* Parameter : none Return : true or false Description : if queue is empty return true. */ bool CQueue::isEmpty() { if (front == rear) return true; else return false; } // isEmpty /* Parameter : none Return : queue length Description : get queue's length. */ int CQueue::itsLength() { int iLen = 0; Node* pNode = front; while (pNode != rear) { ++iLen; pNode = pNode->pNext; } return iLen; } // itsLength /* Parameter : none Return : true or false Description : visit queue every element. */ bool CQueue::Traverse() { Node* pNode = front->pNext; while(pNode) { cout<<pNode->data<<endl; pNode = pNode->pNext; } return true; } // Traverse /* Parameter : none Return : none Description : destroy queue no matter empty or not. */ CQueue::~CQueue() { while(front) { rear = front->pNext; delete front; front = rear; } } // default destructor

//----------------------------------------------------------------------------- // Copyright (c) 2009 eryar All rights reserved. // // File : main.cpp // Author : eryar@163.com // Date : 2010-01-02 // Version : 1.0v // // Description : Queue class implenment. // //============================================================================= #include "queue.h" int main(int argc, char* argv[]) { char x, y; CQueue queue; cout<<"queue length is : "<<queue.itsLength()<<endl; queue.EnQueue('a'); queue.EnQueue('b'); queue.EnQueue('c'); queue.DeQueue(x); queue.DeQueue(y); cout<<"queue length is : "<<queue.itsLength()<<endl; cout<<"first DeQueue element is : "<<x<<endl; cout<<"then DeQueue element is : "<<y<<endl; queue.Traverse(); return 0; }

Program output:

queue length is : 0
queue length is : 1
first DeQueue element is : a
then  DeQueue element is : b
c
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