基于动态数组的队列实现

//--------------DQueue.h------------------#include<iostream>#ifndef DQUEUE#define DQUEUEtypedef int QueueElement;class Queue{public:Queue(int numElements=128);Queue(const Queue & original);~Queue();    const Queue & operator=(const Queue & rightHandSide);bool empty() const;void enqueue(const QueueElement & value);void display(ostream & out) const;QueueElement front() const;void dequeue();private:int myFront,    myBack;int myCapacity;QueueElement *myArray;};#endif

//-------------DQueue.cpp-------------------#include<iostream>#include<cassert>#include<new>using namespace std;#include"DQueue.h"Queue::Queue(int numElements){assert(numElements>0);myCapacity=numElements;myArray=new (nothrow) QueueElement[myCapacity];if(myArray!=0){myFront=0;myBack=0;}else{cerr<<"Inadequate memory to allocate stack \n";exit(1);}}Queue::Queue(const Queue & original):myCapacity(original.myCapacity), myFront(original.myFront),myBack(original.myBack){myArray=new (nothrow) QueueElement[myCapacity];if(myArray!=0)for(int pos=myFront;pos!=myBack;pos=(pos+1)%myCapacity)myArray[pos]=original.myArray[pos];else{cerr<<"***Inadequate memory to allocate stack ***\n";exit(1);}}Queue::~Queue(){delete [] myArray;}const Queue & Queue::operator=(const Queue & rightHandSide){if(this!=&rightHandSide){if(myCapacity!=rightHandSide.myCapacity){delete [] myArray;myCapacity=rightHandSide.myCapacity;myArray=new (nothrow) QueueElement[myCapacity];if(myArray==0){cerr<<"";exit(1);}}myFront=rightHandSide.myFront;myBack=rightHandSide.myBack;for(int pos=myFront;pos!=myBack;pos=(pos+1)%myCapacity) myArray[pos]=rightHandSide.myArray[pos];}return *this;}bool Queue::empty() const{return (myFront==myBack);}void Queue::enqueue(const QueueElement & value){int newBack=(myBack+1)%myCapacity;if(newBack!=myFront){myArray[newBack]=value;myBack=newBack;}else{cerr<<"***The queue is full---can't add new value***\n";exit(1);}}void Queue::display(ostream & out) const{for(int i=myFront;i!=myBack;i=(i+1)%myCapacity)out<<myArray[i]<<" ";cout<<endl;}QueueElement Queue::front() const{if(!empty())    return (myArray[myFront]);else{cerr<<"***The queue is empty--returning a garbage value***\n";QueueElement garbage;return garbage;}}void Queue::dequeue(){if(!empty()){myFront=(myFront+1)%myCapacity;}else{cerr<<"***The queue is empty,can't remove a value.***\n";}}

//-----------DQueue_main.cpp--------------#include<iostream>using namespace std;#include"DQueue.h"int main(){cout<<"Enter the queue's capacity: ";    int cap;    cin>>cap;Queue q(cap);/*////                */return 0;}