C++实现循环队列

本文实例为大家分享了C++实现循环队列的具体代码，供大家参考，具体内容如下

circularQueue.h

#pragma once
#pragma once
#ifndef CIRCULARQUEUE_H
#define CIRCULARQUEUE_H

#include<iostream>
#include<ostream>
using std::cout;
using std::cin;
using std::endl;
using std::ostream;
template<class T> class cirQueue;

template<typename T>
class cirQueue
{
public:
 cirQueue(int sz);
 ~cirQueue();
 void push(const T& elem);//进队
 void pop(T& elem);//出队
 bool empty();//查看队列是否为空
 int getSize();//返回队列中元素的个数
 void clearQueue();//清空队列中的元素
 void print();//打印队列中的元素
 int getfront() { return front; }
 int getrear() { return rear; }
 bool getTop(T& elem);//读取队列首个元素

 template<typename T>
 friend ostream& operator<<(ostream& os, cirQueue<T>& queue);

private:
 bool _full()const;//判断队列是否已满
 int maxsize;//队列最大的空间
 T* element;//存放于队列中的元素数组
 int front;//模拟队头指针
 int rear;//模拟队尾指针
};

template<typename T>
cirQueue<T>::cirQueue(int sz) {
 maxsize = sz;
 element = new T[maxsize];
 if (element == nullptr)
 cout << "内存分配失败" << endl;
 front = 0;
 rear = 0;
}

template<typename T>
cirQueue<T>::~cirQueue() {
 if (element != nullptr)
 delete element;
}

//进队
template<typename T>
void cirQueue<T>::push(const T& elem) {//需要保证队尾指针位置与首个元素相差一个位置
 if (rear > (maxsize - 1))
 rear -= maxsize ;
 if (front > (maxsize - 1))
 front -= maxsize ;
 if (!_full()) {//队列未满的情况
 element[rear++] = elem;//队尾向后移动一位
 //++rear;
 }
 else {
 cout << "队列已满，不能插入！" << endl;
 return;
 }
}

//出队
template<typename T>
void cirQueue<T>::pop(T& elem) {
 if (rear > (maxsize - 1))
 rear -= (maxsize - 1);
 if (front > (maxsize - 1))
 front -= (maxsize - 1);
 if (!empty()) {//队列未空的情况
 elem = element[front++];//队头向后移动一位
 element[front - 1] = 0;//置零
 }
 else {
 cout << "队列已空！" << endl;
 return;
 }
}

//查看队列是否为空
template<typename T>
bool cirQueue<T>::empty() {
 if (front == rear)//待定
 return true;
 return false;
}

//返回队列中元素的个数
template<typename T>
int cirQueue<T>::getSize() {
 int num = 0;
 if (front <= rear)
 return rear - front;
 else
 return maxsize - front + rear + 1;
}

//清空队列中的元素
template<typename T>
void cirQueue<T>::clearQueue() {
 if (!empty())
 {
 int Index = 0;
 while (front < rear) {//front逼近rear
  element[front++] = 0;
  if (front == rear)
  return;
 }
 if (rear < front) {
  while (front <= maxsize - 1)//删除front至数组尾端的数据
  element[front++] = 0;
  front -= maxsize;
  while (front < rear) {//删除front至rear的数据
  element[front++] = 0;
  if (front == rear)
   return;
  }
 }
 }
}

//打印队列中的元素
template<typename T>
void cirQueue<T>::print() {//与clearQueue函数原理一致，将front替换为Index
 if (!empty())
 {
 int Index = front;
 while (Index < rear) {
  cout << element[Index++] << " ";
  if (Index == rear) {
  cout << endl;
  return;
  }
 }
 if (rear < Index) {
  while (Index <= maxsize - 1)
  cout << element[Index++] << " ";
  Index -= maxsize;
  while (Index < rear) {
  cout << element[Index++] << " ";
  if (Index == rear) {
   cout << endl;
   return;
  }
  }
 }
 }
}

//读取队列首个元素
template<typename T>
bool cirQueue<T>::getTop(T& elem) {
 if (!empty()) {
 elem = element[front];
 return true;
 }
 return false;
}

template<typename T>
ostream& operator<<(ostream& os, cirQueue<T>& queue) {
 os << "队列中的元素数量为：" << queue.getSize() << endl;
 return os;
}

//判断队列是否已满
template<typename T>
bool cirQueue<T>::_full()const {
 if (front - rear == 1 || front - rear == -maxsize + 1)
 return true;
 return false;
}

#endif // !CIRCULARQUEUE_H

main.cpp

#include"CircularQueue.h"

int main()
{
 cirQueue<int> cq(20);
 int a = 0;
 for (int i = 0; i < 19; i++)
 {
 cq.push(i);
 }
 cq.print();
 cout << cq;
 for (int i = 0; i < 20; i++)
 {
 cq.pop(a);
 }
 cout << cq;//此时front=rear=19
 cout << cq.getfront() << "  " << cq.getrear() << endl;
 //for (int i = 19; i < 25; i++)
 //{
 // cq.push(i);
 //}
 cq.push(19);
 cq.print();
 cout << cq.getfront() << "  " << cq.getrear() << endl;
 cout << endl << endl;
 cq.push(20);
 cq.getTop(a);
 cout << a << endl;
 cq.print();
 cout << cq.getfront() << "  " << cq.getrear() << endl;
 return 1;
}

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