Demo

循环队列

#include <iostream>
using namespace std;

#define MAXQSIZE 100
typedef int QElemType;

typedef struct
{
	QElemType* base;
	int front;	//头指针
	int rear;	//尾指针
}SqQueue;

//初始化一个空队列
int InitQueue(SqQueue& Q)
{
	Q.base = new QElemType[MAXQSIZE];
	if (!Q.base) return 0;
	Q.front = Q.rear = 0;
	return 1;
}

int QueueLength(SqQueue Q)
{
	return(Q.rear - Q.front + MAXQSIZE) % MAXQSIZE;
}

//入队
int EnQueue(SqQueue& Q, QElemType e)
{
	//rear移动+1取余等于front则队满
	if ((Q.rear + 1) % MAXQSIZE == Q.front)
		return 0;
	Q.base[Q.rear] = e;
	Q.rear = (Q.rear + 1) % MAXQSIZE;	//队尾指针加1/地址循环
}

//出队--删除队头元素,用e返回其值
int DeQueue(SqQueue& Q, QElemType& e)
{
	if (Q.front == Q.rear) return 0;	//队空
	e = Q.base[Q.front];
	Q.front = (Q.front + 1) % MAXQSIZE;	//对头指针+1
	return 1;
}

QElemType GetHead(SqQueue Q)
{
	if (Q.front != Q.rear)
		return Q.base[Q.front];
}

int main()
{
	SqQueue Q;
	QElemType e;
	InitQueue(Q);
	int n;
	cout << "请输入入队个数: ";
	cin >> n;
	cout << "请依次输入入队的数据: " << endl;
	for (int i = 0; i < n; i++)
	{
		cin >> e;
		EnQueue(Q, e);
	}
	cout << "GetHead: ";
	cout << GetHead(Q) << endl;
	cout << "出队: " << endl;
	for (int i = 0; i < n; i++)
	{
		DeQueue(Q, e);
		cout << e << endl;
	}
	return 0;
}

链队

#include <iostream>
using namespace std;

#define MAXQSIZE 100
typedef int QElemType;

typedef struct QNode
{
	QElemType data;
	struct QNode* next;
}QNode, * QueuePtr;

typedef struct
{
	QueuePtr front;
	QueuePtr rear;
}LinkQueue;


int InitQueue(LinkQueue& Q)
{
	Q.front = Q.rear = new QNode;	//生成新结点作为头结点,队头和队尾指针指向此结点
	Q.front->next = NULL;			//头结点指针域为空
	return 1;
}
//入队--插入元素e到队尾
int EnQueue(LinkQueue& Q, QElemType e)
{
	QueuePtr p = new QNode;
	p->data = e;
	p->next = NULL;
	Q.rear->next = p;
	Q.rear = p;
	return 1;
}
//出队--删除队头元素,用e返回值
int DeQueue(LinkQueue& Q, QElemType& e)
{
	if (Q.front == Q.rear)return 0;
	QueuePtr p = Q.front->next;			//p指向队头元素
	e = p->data;						//e保存队头元素值
	//头结点指向的前一个指向p队头的next,断掉原队头
	Q.front->next = p->next;			//修改头结点指针域
	if (Q.rear == p)Q.rear = Q.front;	//如果最后一个元素被删除,队尾指针指向头结点
	delete p;
	return 1;
}

QElemType GetHead(LinkQueue Q)
{
	if (Q.front != Q.rear)
		return Q.front->next->data;
	return 0;
}

int main()
{
	LinkQueue Q;
	QElemType e;
	InitQueue(Q);
	int n;
	cout << "请输入入队个数: ";
	cin >> n;
	cout << "请依次输入入队的数据: " << endl;
	for (int i = 0; i < n; i++)
	{
		cin >> e;
		EnQueue(Q, e);
	}
	cout << "GetHead: ";
	cout << GetHead(Q) << endl;
	cout << "出队: " << endl;
	for (int i = 0; i < n; i++)
	{
		DeQueue(Q, e);
		cout << e << endl;
	}
	return 0;
}