C语言实现链队列代码

[code]#include <stdio.h>

/* 队列的结构体 */
typedef int DataType;
#define NODE_LEN sizeof(NODE) 

/* 队列的节点 */
typedef struct stNode
{
    DataType data;
    struct stNode* next;
}NODE;

/* 队列 */
typedef struct stQueue
{
    NODE* head;  //队列的头
    NODE* tail; //队列的尾
}QUEUE;

/* 初始化队列,不带头结点*/
int initQueue(QUEUE* INQueue)
{

    INQueue->head = NULL;
    INQueue->tail = NULL;

    return 0;
}

/* 从队尾插入一个元素 */
int enQueue(QUEUE* InQueue,DataType InData)
{
    NODE* pNewNode = (NODE*)malloc(NODE_LEN);
    if (pNewNode == NULL)
    {
        return -1;
    }

    pNewNode->data = InData;
    pNewNode->next = NULL;

    /* 判断，现在队列里面有没有节点 */
    if (InQueue->head == NULL)
    {
        InQueue->head = pNewNode;
        InQueue->tail = pNewNode;
    }
    else
    {
        InQueue->tail->next = pNewNode;
        InQueue->tail = pNewNode;
    }

    return 0;
}

/* 遍历该队列 */
int visitQueue(QUEUE InQueue)
{
    QUEUE* pstTemp = &InQueue;

    /* 判断队列是否为空队列 */
    if (pstTemp->head == NULL)
    {
        printf("visitQueue: this queue is empty\n");
        return -1;
    }

    /* 遍历该队列中的所有元素 */
    while (pstTemp->head->next != NULL)
    {
        printf("%d ", pstTemp->head->data);
        pstTemp->head = pstTemp->head->next;
    }
    printf("%d \n", pstTemp->head->data);

    return 0;
}

/* 出队列 */
int delQueue(QUEUE* InQueue,DataType* OutData)
{
    if (InQueue->head == NULL)
    {
        printf("delQueue: this queue is empty\n");
        return -1;
    }

    *OutData = InQueue->head->data;

    NODE* pstTemp = InQueue->head;
    InQueue->head = InQueue->head->next;

    delete pstTemp;
    return 0;
}

/* 判断队列是否是空队列 */
int isEmptyQueue(QUEUE InQueue)
{
    if (InQueue.head == NULL)
    {
        return 0; //是空队列
    }
    return 1; //不是空队列
}

int main()
{
    /* 创建一个队列 */
    QUEUE queue;
    DataType data;

    initQueue(&queue);

    /* 入队列 */
    enQueue(&queue, 12);
    enQueue(&queue, 11);
    enQueue(&queue, 2);
    visitQueue(queue);

    /* 出队列 */
    delQueue(&queue, &data);
    visitQueue(queue);
    printf("data = %d\n", data);

    visitQueue(queue);

    if (0 == isEmptyQueue(queue))
    {
        printf("This is empty queue\n");
    }
    else
    {
        printf("This is not empty queue\n");
    }
    return 0;
}