数据结构之队列的链式结构-初始化-判断队列是否为空-入队-出队-获取队头元素

 数据结构之队列的链式结构基本操作-初始化-判断队列是否为空-入队-出队-获取队头元素

完整可运行代码：

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

typedef int ElemType;

typedef struct QueueNode
{
	ElemType data;
	struct QueueNode *next;
}QueueNode;

typedef struct 
{
	QueueNode *front;
	QueueNode *rear;
}Queue;

//初始化
Queue* initQueue()
{
	Queue *q = (Queue*)malloc(sizeof(Queue));
	QueueNode *node = (QueueNode*)malloc(sizeof(QueueNode));
	node->data = 0;
	node->next = NULL;
	q->front = node;
	q->rear = node;
	return q;
}

//判断队列是否为空为空
int isEmpty(Queue *q)
{
	if (q->front == q->rear)
	{
		return 1;
	}
	else
	{
		return 0;
	}
}

//入队
void equeue(Queue *q, ElemType e)
{
	QueueNode *node = (QueueNode*)malloc(sizeof(QueueNode));
	node->data = e;
	node->next = NULL;
	q->rear->next = node;
	q->rear = node;
}

//出队
int dequeue(Queue *q, ElemType *e)
{
	if (isEmpty(q))
	{
		printf("空的\n");
		return 0;
	}

	QueueNode *node = q->front->next;
	*e = node->data;
	q->front->next = node->next;
	if (q->rear == node)
	{
		q->rear = q->front;
	}
	free(node);
	return 1;
}

//获取队头元素
ElemType getFront(Queue *q)
{
	if (isEmpty(q))
	{
		printf("空的\n");
		return 0;
	}
	return q->front->next->data;
}


int main()
{
	Queue *q = initQueue();
	equeue(q, 10);
	equeue(q, 20);
	equeue(q, 30);
	equeue(q, 40);
	equeue(q, 50);
	ElemType e;
	dequeue(q, &e);
	printf("出队%d\n", e);
	dequeue(q, &e);
	printf("出队%d\n", e);
	printf("%d\n", getFront(q));
	return 0;
}

运行结果：