听了国嵌唐老师的课，用C语言实现如下：

数据结构：链式队列的优化实现_#define


LinkQueue.h

#ifndef _LINKQUEUE_H_
#define _LINKQUEUE_H_

typedef void LinkQueue;

LinkQueue* LinkQueue_Create();

void LinkQueue_Destroy(LinkQueue* queue);

void LinkQueue_Clear(LinkQueue* queue);

int LinkQueue_Append(LinkQueue* queue, void* item);

void* LinkQueue_Retrieve(LinkQueue* queue);

void* LinkQueue_Header(LinkQueue* queue);

int LinkQueue_Length(LinkQueue* queue);

#endif

LinkQueue.c

#include <malloc.h>
#include <stdio.h>
#include "LinkQueue.h"

typedef struct _tag_LinkQueueNode TLinkQueueNode;
struct _tag_LinkQueueNode
{
    TLinkQueueNode* next;
    void* item;
};

typedef struct _tag_LinkQueue
{
    TLinkQueueNode* front;
    TLinkQueueNode* rear;
    int length;
} TLinkQueue;

LinkQueue* LinkQueue_Create() // O(1)
{
    TLinkQueue* ret = (TLinkQueue*)malloc(sizeof(TLinkQueue));
    
    if( ret != NULL )
    {
        ret->front = NULL;
        ret->rear = NULL;
        ret->length = 0;
    }
    
    return ret;
}

void LinkQueue_Destroy(LinkQueue* queue) // O(n)
{
    LinkQueue_Clear(queue);
    free(queue);
}

void LinkQueue_Clear(LinkQueue* queue) // O(n)
{
    while( LinkQueue_Length(queue) > 0 )
    {
        LinkQueue_Retrieve(queue);
    }
}

int LinkQueue_Append(LinkQueue* queue, void* item) // O(1)
{
    TLinkQueue* sQueue = (TLinkQueue*)queue;
    TLinkQueueNode* node = (TLinkQueueNode*)malloc(sizeof(TLinkQueueNode));
    int ret = (sQueue != NULL ) && (item != NULL) && (node != NULL);
    
    if( ret )
    {
        node->item = item;
        
        if( sQueue->length > 0 )
        {
            sQueue->rear->next = node;
            sQueue->rear = node;
            node->next = NULL;
        }
        else
        {
            sQueue->front = node;
            sQueue->rear = node;
            node->next = NULL;
        }
        
        sQueue->length++;
    }
    
    if( !ret )
    {
        free(node);
    }
    
    return ret;
}

void* LinkQueue_Retrieve(LinkQueue* queue) // O(1)
{
    TLinkQueue* sQueue = (TLinkQueue*)queue;
    TLinkQueueNode* node = NULL;
    void* ret = NULL;
    
    if( (sQueue != NULL) && (sQueue->length > 0) )
    {
        node = sQueue->front;
        
        sQueue->front = node->next;
        
        ret = node->item;
        
        free(node);
        
        sQueue->length--;
        
        if( sQueue->length == 0 )
        {
            sQueue->front = NULL;
            sQueue->rear = NULL;
        }
    }
    
    return ret;
}

void* LinkQueue_Header(LinkQueue* queue) // O(1)
{
    TLinkQueue* sQueue = (TLinkQueue*)queue;
    void* ret = NULL;
    
    if( (sQueue != NULL) && (sQueue->length > 0) )
    {
        ret = sQueue->front->item;
    }
    
    return ret;
}

int LinkQueue_Length(LinkQueue* queue) // O(1)
{
    TLinkQueue* sQueue = (TLinkQueue*)queue;
    int ret = -1;
    
    if( sQueue != NULL )
    {
        ret = sQueue->length;
    }
    
    return ret;
}

main.c

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

/* run this program using the console pauser or add your own getch, system("pause") or input loop */

int main(int argc, char *argv[]) 
{
    LinkQueue* queue = LinkQueue_Create();
    int a[10] = {0};
    int i = 0;
    
    for(i=0; i<10; i++)
    {
        a[i] = i + 1;
        
        LinkQueue_Append(queue, a + i);
    }
    
    printf("Header: %d\n", *(int*)LinkQueue_Header(queue));
    printf("Length: %d\n", LinkQueue_Length(queue));
    
//    LinkQueue_Clear(queue);
    
    while( LinkQueue_Length(queue) > 0 )
    {
        printf("Retrieve: %d\n", *(int*)LinkQueue_Retrieve(queue));
    }
    
    LinkQueue_Destroy(queue);
    
    return 0;
}

运行效果：

数据结构：链式队列的优化实现_#define_02