循环队列入队出队判队空队满

循环队列：

结构：

typedef struct
{
	ElemType *data;  //数据域
	int front;  //队头
	int rear;  //队尾   下标代替指针
}SqQueue;

1. 初始化队列
   初始化队列让Q.front = Q.rear = 0 即可
2. 判队空
   判空 判断等式是否成立： Q.front == Q.rear
3. 判队满
   判队满 因为循环队列会空出来一个位置
   (Q.rear + 1) % MAXSIZE == Q,front
   
4. 入队
   让队尾指针后移，后移之后再输入元素
5. 出队

代码：

#ifndef _SQQUEUE_H_
#define _SQQUEUE_H_

#include <iostream>
#include <fstream>
using namespace std;

#define OK 1
#define ERROR 0
#define MAXSIZE 5

typedef int Status;
typedef int ElemType;

typedef struct
{
	ElemType *data;  //数据域
	int front;  //队头
	int rear;  //队尾   下标代替指针
}SqQueue;

Status initSqQueue(SqQueue &Q)
{
	Q.data = (ElemType *)malloc(sizeof(ElemType) * MAXSIZE);
	if (!Q.data)
	{
		cout << "空间不足";
		return ERROR;
	}
	Q.front = Q.rear = 0;
}

bool isEmpty(SqQueue &Q)
{
	if (Q.front == Q.rear)
		return true;
	return false;
}

bool isFull(SqQueue &Q)
{
	if ((Q.rear + 1) % MAXSIZE == Q.front)
		return true;
	return false;
}

Status EnQueue(SqQueue &Q, ElemType e)
{
	if (isFull(Q))
	{
		cout << "队满，无法插入元素\n";
		return OVERFLOW;
	}
	Q.rear = (Q.rear + 1) % MAXSIZE;
	Q.data[Q.rear] = e;
	return OK;
}

Status DeQueue(SqQueue &Q, ElemType &e)
{
	if (isEmpty(Q))
	{
		cout << "队空，无法删除元素\n";
		return ERROR;
	}
	Q.front = (Q.front + 1) % MAXSIZE;
	e = Q.data[Q.front];
	return OK;
}

void Visit(SqQueue Q)  //遍历循环队列
{
	int p = (Q.front + 1) % MAXSIZE;
	if (p <= Q.rear)
	{
		for (p; p <= Q.rear; p++)
			cout << Q.data[p] <<" ";
	}
	else
	{
		for (p; p < MAXSIZE; p++)
			cout << Q.data[p] <<" ";
		p = 0;
		for (p; p <= Q.rear; p++)
			cout << Q.data[p] <<" ";
	}
	cout << endl;
}
#endif