Establishing the queues circulation operation

First, the basic idea

1. initialization built empty queue, so that front = rear = 0;

2. When the tail pointer is incremented insert elements, delete the head elements by a head pointer ,;

3. The head pointer always points to the head elements, the end position of the tail pointer to the next element, as shown;

4. The annular space fanciful

(1) in a state sequentially inserted J5, J6, J7 to give b, sequentially deleted J3, J4, J5 c obtained in a state;

(2) when the queue is full or empty have front = rear, two solutions: First Flag is set, the last two is to reserve a space, a full condition;

5. If a user can not estimate the maximum length of the queue, the queue using the endless chain;

6. Using one-dimensional array to simulate a circular queue is to be noted the relationship between the Front and rear, on the queue length in terms of demand, not directly rear-front, a case is supposed

6 is a memory space, the front of the queue to fill 0, 5 REAR, now put out of a queue element, then add 1 to front, the subscript now vacant space for 0,

Now insert an element value of 0 is the rear, it is required at this time queue length, it is the (rear-front + max)% max;

Second, the code is as follows

/*
项目名称：顺序循环队列的建立与基本操作

编译环境：VC++ 2008

作者相关：。。。

最后修改：2019.6.23


学习目标：初始化、销毁、清空、判空、求长、返回队头元素、插入元素、删除元素、输出队列中元素

注意事项：1.测试所有功能是否正常

2.Q.rear-Q.front + MAXQSIZE % MAXQSIZE

一维数组模拟的循环队列，假设有5块内存，front增加到5了，那么5之前的空间可以使用，
这样rear就到1所在的空间，这样rear就比5小了

*/
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#define MAXQSIZE 100
#define ERROR    0
#define OK       1

typedef int      ElemType;
typedef bool     Status;

typedef struct{

	ElemType *base;//初始化动态分配存储空间
	int front;//若队列不空，指向队列头元素
	int rear;//若队列不空，指向队列尾元素的下一个位置

}SqCQueue;

Status InitQueue(SqCQueue *Q);

Status DestroyQueue(SqCQueue *Q);

Status ClearQueue(SqCQueue *Q);

Status EmptyQueue(SqCQueue Q);

int    LengthQueue(SqCQueue Q);

Status GetHead(SqCQueue Q,ElemType *e);

Status EnQueue(SqCQueue *Q,ElemType e);

Status DeQueue(SqCQueue *Q,ElemType *e);

Status TravelQueue(SqCQueue Q);

void   visit(ElemType c);

int main()
{
	SqCQueue q;
	ElemType e;

	InitQueue(&q);

	if(EmptyQueue(q))
		printf("循环队列为空!\n\n");
	else
		printf("循环队列非空!\n\n");

	srand(time(0));
	for(int i=0;i<10;i++)
	{
		e = rand()%100+1;
		EnQueue(&q,e);
	}
	TravelQueue(q);

	int k = LengthQueue(q);
	printf("循环队列长度为:%d \n\n",k);

	GetHead(q,&e);
	printf("循环队列队首为:%d \n\n",e);

	DeQueue(&q,&e);
	DeQueue(&q,&e);
	printf("循环队列第二次删除的元素为:%d \n\n",e);
	TravelQueue(q);

	EnQueue(&q,101);
	printf("插入新元素后,");
	TravelQueue(q);

	ClearQueue(&q);
	DestroyQueue(&q);

	return 0;
}

Status InitQueue(SqCQueue *Q)
{
	Q->base = (ElemType *)malloc(MAXQSIZE*sizeof(ElemType));
	if(!Q->base)
		return ERROR;
	Q->front = Q->rear = 0;

	return OK;
}

Status DestroyQueue(SqCQueue *Q)
{
	free(Q->base);
	return OK;
}

Status ClearQueue(SqCQueue *Q)
{
	Q->front = Q->rear = 0;

	return OK;
}

Status EmptyQueue(SqCQueue Q)
{
	if(Q.front == Q.rear)
		return true;
	else
		return false;
}

int    LengthQueue(SqCQueue Q)
{
	return (Q.rear-Q.front + MAXQSIZE) % MAXQSIZE;
}

Status GetHead(SqCQueue Q,ElemType *e)
{
	if(EmptyQueue(Q))
		return ERROR;
	else
	{
		*e = *(Q.base+Q.front);
		return OK;
	}
}

Status EnQueue(SqCQueue *Q,ElemType e)
{
	if((Q->rear+1)%MAXQSIZE == Q->front)//队列满,即rear指向front之前的位置时
		return ERROR;

	*(Q->base+Q->rear) = e;
	Q->rear = (Q->rear+1) % MAXQSIZE;//假设max为6，本来rear=5(从0开始计数的)，
	//现在要到第一块内存，rear要等于0，实现了循环
	return OK;

}

Status DeQueue(SqCQueue *Q,ElemType *e)
{
	if(EmptyQueue(*Q))
		return ERROR;
	else
	{
		*e = *(Q->base+Q->front);
		Q->front = (Q->front+1) % MAXQSIZE;//指向它的下个位置
		return OK;
	}
}

Status TravelQueue(SqCQueue Q)
{
	printf("顺序循环队列内容: \n\n");
	while(Q.front!=Q.rear)
	{
		visit(*(Q.base+Q.front));
		Q.front = (Q.front+1) % MAXQSIZE;
	}
	printf("\n\n");
	return OK;
}

void   visit(ElemType c)
{
	printf("%d ",c);
}