队列的链式实现

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

typedef struct node3
{
    int nValue;
    struct node3 *pNext;
}MyQueue;

typedef struct node4
{
    MyQueue *pHead;
    MyQueue *pTail;
    int nCount;
}Queue;

void q_Init(Queue **pQueue)//注意这里传的是二级指针，传一级的属于值传递，也可以选择不含参数，返回一个一级指针的做法
{
    *pQueue  = (Queue*)malloc(sizeof(Queue));
    (*pQueue)->pHead = NULL;
    (*pQueue)->pTail = NULL;
    (*pQueue)->nCount = 0;
}

void q_Push(Queue *pQueue,int nNum)
{
    if(pQueue == NULL)return;

    MyQueue *pTemp = NULL;
    pTemp = (MyQueue*)malloc(sizeof(MyQueue));
    pTemp->nValue = nNum;//队列实际上是尾插入头删除的单链表
    pTemp->pNext = NULL;

    if(pQueue->pHead == NULL)
    {
        pQueue->pHead = pTemp;
    }
    else
    {
        pQueue->pTail->pNext = pTemp;
    }
    pQueue->pTail = pTemp;

    pQueue->nCount++;
}

int q_Pop(Queue *pQueue)
{
    if(pQueue == NULL || pQueue->nCount == 0)return -1;

    int nNum;
    MyQueue *pDel = NULL;

    pDel = pQueue->pHead;
    nNum = pDel->nValue;

    pQueue->pHead = pQueue->pHead->pNext;
    free(pDel);
    pDel = NULL;
    pQueue->nCount--;
    
    //只有一个元素被弹出之后 尾置空
    if(pQueue->nCount == 0)
    {
        pQueue->pTail = NULL;
    }
    return nNum;
}

int q_IsEmpty(Queue *pQueue)
{
    if(pQueue == NULL)return -1;
    return pQueue->nCount == 0?1:0;
}

int main()
{
    Queue *pQueue = NULL;
    q_Init(&pQueue);
    q_Push(pQueue,1);
    q_Push(pQueue,2);
    q_Push(pQueue,3);
    q_Push(pQueue,4);

    printf("%d
",q_Pop(pQueue));
    printf("%d
",q_Pop(pQueue));
    printf("%d
",q_Pop(pQueue));
    return 0;
}