队列（C语言实现）超级简洁版

数据结构设计

//节点数据结构
typedef struct queue_node
{
	queue_node* next;
	void* data;
}queue_node;

//队列数据结构
typedef struct queue
{
	queue_node* head;
	queue_node* tail;
	int length;
}queue;

接口设计

//创建队列
queue* queue_create();
//入队
queue* queue_push(queue* queue,void *data);
//出队
void* queue_pop(queue* queue);
//释放所有节点
void queue_empty(queue* queue);
//删除队列
void queue_release(queue* queue);

接口实现

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

//创建队列
queue* queue_create()
{
	queue* queue = (struct queue*)malloc(sizeof(struct queue));
	queue_node* node = (struct queue_node*)malloc(sizeof(struct queue_node));
	if (queue == NULL || node == NULL)
		return NULL;
	
	node->data = NULL;
	node->next = NULL;

	queue->head = queue->tail = node;
	queue->length = 0;

	return queue;
}

//入队
queue* queue_push(queue* queue, void* data)
{
	queue_node* node = (struct queue_node*)malloc(sizeof(struct queue_node));
	if (node == NULL)
		return NULL;
	node->data = data;

	queue->tail->next = node;
	queue->tail = node;
	queue->length++;

	return queue;
}

//出队
void* queue_pop(queue* queue)
{
	queue_node* cur = queue->head->next;
	if (cur == NULL)
		return NULL;

	void* data = cur->data;

	queue->head->next = cur->next;

	if (queue->tail == cur)
		queue->tail = queue->head;

	free(cur);
	queue->length--;

	return data;
}

//释放所有节点
void queue_empty(queue* queue)
{
	queue_node* cur;
	queue_node* next;

	cur = queue->head->next;
	while (queue->length--)
	{
		next = cur->next;
		free(cur);
		cur = next;
	}

	queue->head->next = NULL;
	queue->head->data = NULL;
	queue->tail = queue->head;
	queue->length = 0;

	return;
}

//删除队列
void queue_release(queue* queue)
{
	queue_empty(queue);
	free(queue->head);
	free(queue);

	return;
}

测试代码

#include<stdio.h>
#include"tmp.h"

int main()
{
	char a = 'a';
	char b = 'b';
	char c = 'c';

	queue* queue = queue_create();
	printf("%p\n", queue_pop(queue));

	queue_push(queue, &a);
	queue_push(queue, &b);
	queue_push(queue, &c);

	while (queue->length)
		printf("%c\n", *(char*)queue_pop(queue));

	printf("--------------------\n");

	queue_push(queue, &c);
	queue_push(queue, &c);
	queue_push(queue, &a);

	while (queue->length)
		printf("%c\n", *(char*)queue_pop(queue));

	queue_empty(queue);
	printf("%p\n", queue_pop(queue));

	queue_release(queue);

	return 0;
}