队列代码详解（C语言）

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <stdbool.h>
typedef struct QueueNode
{
    struct QueueNode* next;
    int data;
}QueueNode;
//将来的队列
typedef struct Queue
{
    QueueNode *head;
    QueueNode *tail;
}Queue;
//两个指针，放在结构体里用，方便一点，不用传二级指针
void QueueInit(Queue* like);
void QueueTest();
void QueueDestroy(Queue *like);
void QueuePush(Queue* like,int data); 
void QueuePop(Queue* like);
int QueueFront(Queue* like);
int QueueBack(Queue* like);
int QueueSize(Queue* like);
bool QueueEmpty(Queue* like);
int main()
{
    QueueTest();
    return 0;
}
#include "queue.h"
void QueueTest()
{
    //创建Queue类型结构体，里面放了两个Queuenode型的指针
    Queue like;
    QueueInit(&like);
    QueuePush(&like, 1);
    QueuePush(&like, 2);
    QueuePush(&like, 3);
    QueuePush(&like, 4);
    QueuePush(&like, 5);
}
void QueueInit(Queue* like)
{
    assert(like);
    //断言，如果like为空，中止运行并报错
    like->head = NULL;
    like->tail = NULL;
    //置空
}
void QueueDestroy(Queue* like)
{
    assert(like);
    QueueNode* cur = like->head;
    //用cur存下头节点指针
    while (cur != NULL)//这里不要让cur!=like->tail，因为删到最后，cur==like->tail
                       //的时候，最后一个删不掉
    {
        like->head = like->head->next;
        free(cur);
        cur = like->head;
        //先存下一个数据，释放当前，再指向下一个
    }
    like->head = like->tail = NULL; 
    //释放完后，全部置空，避免变成野指针
}
void QueuePush(Queue* like, int data)
{
    assert(like);
    QueueNode* newnode = (QueueNode*)malloc(sizeof(QueueNode));
    newnode->data = data;
    newnode->next = NULL;
    //创建新节点并填充数据
    if (like->head == NULL)
    {
        //如果头为空，头尾指针都指向新节点
        like->head = like->tail = newnode;
    }
    else
    {
        //正常操作插入
        like->tail->next = newnode;
        like->tail = newnode;
}
void QueuePop(Queue* like)
{
    assert(like);
    assert(!QueueEmpty(like));
    //如果like->head为空，!1=0，中止
    QueueNode* con = like->head->next;
    free(like->head);
    like->head = con;
    if (like->head == NULL)
    {
        //此处是为了避免野指针的出现，后续如果数据删完，要求尾数据，没有
        //这个if语句，那就会报错，因为head为NULL，但对tail没有操作
        like->tail == NULL;
    }     
}
//求队列的头数据
int QueueFront(Queue* like)
{
    assert(like);
    assert(!QueueEmpty(like));
    return like->head->data;
}
//求队列的尾数据
int QueueBack(Queue* like)
{
    assert(like);
    assert(!QueueEmpty(like));
    return like->tail->data;
}
//计算队列长度
int QueueSize(Queue* like)
{
    assert(like);
    int n = 0;
    QueueNode* cur = like->head;
    while (cur)
    {
        n++;
        cur = cur->next;
    }
    return n;
}
//判断like->head是否为空
bool QueueEmpty(Queue* like)
{
    assert(like);
    return like->head == NULL;
}