C语言数据结构算法基础之循环队列示例

//定义循环队列
typedef struct _LoopQueue {
	int data[8];		//存放数据
	int start;		//头指针
	int end;		//尾指针
} LoopQueue;

#define TRUE	1
#define FALSE	0
#define SIZE	8
//初始化队列
int init(LoopQueue *lq) {
	lq->start = 0;
	lq->end = 0;
	return TRUE;
}
//判断队列是否为空
int isEmpty(LoopQueue *lq) {
	if (lq->start == lq->end) {
		return TRUE;
	}
	return FALSE;
}
//判断队列是否为满
int isFull(LoopQueue *lq) {
	if ((lq->end + 1) % SIZE == lq->start) {
		return TRUE;
	}
	return FALSE;
}
//获取队列的长度
int getLength(LoopQueue *lq) {
	return (lq->end - lq->start + SIZE) % SIZE;
}
//插入数据
int pushQueue(LoopQueue *lq, int data) {
	if(isFull(lq)) {
		printf("Queue is full.\n");
		return FALSE;
	}
	lq->data[lq->end] = data;
	lq->end = (lq->end + 1) % SIZE;
	return TRUE;
}
//弹出数据
int popQueue(LoopQueue *lq, int *data) {
	if (isEmpty(lq)) {
		printf("Queue is empty.\n");
		return FALSE;
	}
	*data = lq->data[lq->start];
	lq->start = (lq->start + 1) % SIZE;
	return TRUE;
}
//显示队列中的数据
void printQueue(LoopQueue *lq) {
	int index;
	int count;
	count = getLength(lq);
	if (0 == count) {
		printf("No data.\n");
		return;
	}
	for (index = 0; index < count; index++) {
		printf("%d ", lq->data[index]);
	}
	printf("\n");
	return;
}

int main()
{
	int index;
	int num;
	//队列测试代码
	LoopQueue *lq = (LoopQueue *)malloc(sizeof(LoopQueue));
	init(lq);
	printQueue(lq);
	for (index = 0; index < SIZE; index ++) {	//注意这里要放8个数据，但是实际上只能放7个，所以最后一个会报错
		pushQueue(lq, index);
	}
	printQueue(lq);
	for (index = 0; index < SIZE; index ++) {	//同上，会打印一个错误
		if (popQueue(lq, &num)) {
			printf("%d\n", num);
		}
	}
	printQueue(lq);
	return 0;
}