基于链表实现队列

在上一篇博客中，我们实现了顺序队列的编写。现在我们来实现链式队列的编写。

linkqueue.h：

#pragma once

#include
#include
#include

typedef char LinkQueueType;

typedef struct LinkNode{
    LinkQueueType data;
    struct LinkNode* next;
}LinkNode;

typedef struct LinkQueue{
    LinkNode* head;
    LinkNode* tail;
}LinkQueue;

void LinkQueueInit(LinkNode** q);
void LinkQueuePrint(LinkNode* q,const char* msg);
LinkNode* CreateNode(LinkQueueType value);
void LinkQueueDestroy(LinkNode** q);
void LinkQueuePush(LinkNode** q,LinkQueueType value);
void LinkQueuePop(LinkNode** q);
int LinkQueueFront(LinkNode* q,LinkQueueType* value);

linkqueue.c：

#include "linkqueue.h"

void LinkQueueInit(LinkNode** q){
    if(q == NULL){
        return;
    }
    *q = NULL;
}

void LinkQueueDestroy(LinkNode** q){
    if(q == NULL){
        return;
    }
    LinkNode* cur = *q;
    for(;cur != NULL;cur = cur->next){
        free(cur);
    }
    *q = NULL;
}

LinkNode* CreateNode(LinkQueueType value){
    LinkNode* new_node = (LinkNode*)malloc(sizeof(LinkNode));
    new_node->data = value;
    new_node->next = NULL;
    return new_node;
}

void LinkQueuePrint(LinkNode* q,const char* msg){
    printf("[%s]\n",msg);
    LinkNode* cur = q;
    for(;cur != NULL;cur = cur->next){
        printf("[%c] ",cur->data);
    }
    printf("\n");
}

void LinkQueuePush(LinkNode** q,LinkQueueType value){
    if(q == NULL){
        return;
    }
    LinkNode* new_node = CreateNode(value);
    new_node->next = *q;
    *q = new_node;
}

void LinkQueuePop(LinkNode** q){
    if(q == NULL){
        return;
    }
    if(*q == NULL){
        return;
    }
    LinkNode* to_delete = *q;
    *q = (*q)->next;
    free(to_delete);
}

int LinkQueueFront(LinkNode* q,LinkQueueType* value){
    if(q == NULL){
        return 0;
    }
    *value = q->data;
    return 1;
}

test.c：

#include "linkqueue.h"

#define PRINT_HEAD printf("\n============%s============\n",__FUNCTION__)

void test(){
    PRINT_HEAD;
    LinkNode* q;
    LinkQueueInit(&q);
    LinkQueuePrint(q,"队列的初始化");

    LinkQueuePush(&q,'a');
    LinkQueuePush(&q,'b'); 
    LinkQueuePush(&q,'c'); 
    LinkQueuePush(&q,'d');
    LinkQueuePrint(q,"入队列四个元素");

    LinkQueueType value;
    int ret = LinkQueueFront(q,&value);
    printf("ret except 1,actual %d\n",ret);
    printf("front except d,actual %c\n",value);
    LinkQueuePop(&q);
    LinkQueuePrint(q,"出队列一个元素");
       
    ret = LinkQueueFront(q,&value);
    printf("ret except 1,actual %d\n",ret);
    printf("front except c,actual %c\n",value);
    LinkQueuePop(&q); 
    LinkQueuePrint(q,"出队列两个元素");  
            
    ret = LinkQueueFront(q,&value);
    printf("ret except 1,actual %d\n",ret);
    printf("front except b,actual %c\n",value);
    LinkQueuePop(&q); 
    LinkQueuePrint(q,"出队列三个元素");  
                
    ret = LinkQueueFront(q,&value);
    printf("ret except 1,actual %d\n",ret);
    printf("front except a,actual %c\n",value);
    LinkQueuePop(&q); 
    LinkQueuePrint(q,"出队列四个元素");  
                     
    ret = LinkQueueFront(q,&value);
    printf("ret except 0,actual %d\n",ret);
    LinkQueuePop(&q);
    LinkQueuePrint(q,"尝试对空队列操作");  

    LinkQueuePush(&q,'a');
    LinkQueuePush(&q,'b');
    LinkQueuePush(&q,'c');                                                          
    LinkQueuePush(&q,'d');
    LinkQueuePrint(q,"入队列四个元素");
    LinkQueueDestroy(&q);
    LinkQueuePrint(q,"销毁队列");
}

int main(){
    test();
}

结果演示：