C语言数据结构——循环队列

上面的顺序队列会因为前面元素出队而出现空间浪费，所以继续用循环队列来改进。

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#include <stdio.h>
#include <stdlib.h>

#define MAXSIZE 100

typedef int ElemType;

typedef struct{
	ElemType *data;
	int front;
	int rear;
}CircleQueue;

CircleQueue* initCircleQueue()
{
	CircleQueue *q = (CircleQueue*)malloc(sizeof(CircleQueue));
	q->data = (ElemType*)malloc(sizeof(ElemType) * MAXSIZE);
	q->front = 0;
	q->rear = 0;
	return q;
}
//初始化循环队列

int isEmpty(CircleQueue *q)
{
	if(q->front == q->rear)
	{
		printf("Empty.\n");
		return 1;
	}
	else
	{
		return 0;
	}
}
//判断循环队列是否为空

int isFull(CircleQueue *q)
{
	if((q->rear + 1) % MAXSIZE == q->front)
	{
		printf("Full.\n");
		return 1;
	}
	else
	{
		return 0;
	}
}
//判断循环队列是否已满

int enQueue(CircleQueue *q,ElemType e)
{
	if(isFull(q))
	{
		return 0;
	}
	q->data[q->rear] = e;
	q->rear = (q->rear + 1) % MAXSIZE;
	return 1;
}
//入队

ElemType deCircleQueue(CircleQueue *q)
{
	if(isEmpty(q))
	{
		return 0;
	}
	ElemType e = q->data[q->front];
	q->front = (q->front + 1) % MAXSIZE;
	return e;
}
//出队

int getCircleHead(CircleQueue *q,ElemType *e)
{
	if(isEmpty(q))
	{
		return 0;
	}
	*e = q->data[q->front];
	return 1;
}
//获取头元素

int main()
{
	CircleQueue *q = initCircleQueue();
	enQueue(q,10);
	enQueue(q,20);
	enQueue(q,30);
	enQueue(q,40);
	printf("%d\n",deCircleQueue(q));
	printf("%d\n",deCircleQueue(q));
	ElemType e;
	getCircleHead(q,&e);
	printf("%d\n",e);
	return 0;
}