队列的简单操作

队列，是先进先出（FIFO）的线性表。在具体应用中通常用链表或者数组来实现。队列只允许在后端（称为rear）进行插入操作，在前端（称为front）进行删除操作。

queue.h

Code:

#ifndef _QUEUE_H

#define _QUEUE_H

#define Type int

#ifdef _MSC_VER

#define bool int

#define true 1

#define false 0

#else

#include <stdbool.h>

#include <stdint.h>

#endif

struct queue;

struct queue *init_queue();

void destory_queue(struct queue *q);

void clear_queue(struct queue *q);

bool en_queue(struct queue *q, Type data);

bool de_queue(struct queue *q);

Type gethead(struct queue *q);

bool queue_empty(struct queue *q);

int queue_size(struct queue *q);

void print_queue(struct queue *q);

#endif

queue.c

Code:

#include "queue.h"

#include <stdio.h>

#include <stdlib.h>

#include <assert.h>

struct queue_node {

Type data;

struct queue_node *next;

};

struct queue {

struct queue_node *front;

struct queue_node *rear;

};

struct queue *init_queue()

{

struct queue *q = (struct queue *)malloc(sizeof(struct queue));

if (q == NULL)

return NULL;

q->front = q->rear = (struct queue_node *)malloc(sizeof(struct queue_node));

if (q->front == NULL)

return NULL;

q->front->next = NULL;

return q;

}

void destory_queue(struct queue *q)

{

assert(q != NULL);

while (q->front != NULL) {/*also free head node*/

q->rear = q->front->next;

free (q->front);

q->front = q->rear;

}

free(q);

q = NULL;

}

void clear_queue(struct queue *q)

{

assert(q != NULL);

struct queue_node *h, *p;

h = q->front->next;

q->rear = q->front;

q->front->next = NULL;

while (h != NULL) {

p = h;

h = h->next;

free(p);

}

}

bool en_queue(struct queue *q, Type data)

{

assert(q != NULL);

struct queue_node *p = (struct queue_node *)malloc(sizeof(struct queue_node));

if (p == NULL)

return false;

p->data = data;

p->next = NULL;

q->rear->next = p;

q->rear = p;

return true;

}

bool de_queue(struct queue *q)

{

assert(q != NULL);

if (q->front == q->rear)

return false;

struct queue_node *p = q->front->next;

q->front->next = p->next;

if (q->rear == p)

q->rear = q->front;/*null*/

free(p);

return true;

}

bool queue_empty(struct queue *q)

{

assert(q != NULL);

if (q->front->next == NULL)

return true;

else

return false;

}

int queue_size(struct queue *q)

{

struct queue_node *p = q->front;

int i = 0;

while (p != q->rear) {

i++;

p = p->next;

}

return i;

}

Type gethead(struct queue *q)

{

assert(q != NULL);

if (q->front != q->rear)

return q->front->next->data;

else

return 0;

}

void print_queue(struct queue *q)

{

assert(q != NULL);

struct queue_node *p = q->front;

while (p->next != NULL) {

p = p->next;

printf("%d ", p->data);

}

}

主函数

Code:

#include <stdio.h>

#include "queue.h"

int main()

{

struct queue *q = init_queue();

en_queue(q, 2);

en_queue(q, 1);

en_queue(q, 3);

en_queue(q, 5);

de_queue(q);

print_queue(q);

destory_queue(q);

return 0;

}