C语言 链表的使用（链表的增删查改，链表逆转，链表排序）

//链表的使用

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
#include<string.h>

//定义链表结构体
struct LinkCode{
    int num;
    char sname[50];
    struct LinkCode * linknext;
};

//静态链表
void Linkone(){
    struct LinkCode n1, n2, n3, n4, n5;
    struct LinkCode * head = NULL;
    //初始化变量
    n1.num = 1;
    sprintf(n1.sname, "小明");
    n1.linknext = &n2;

    n2.num = 2;
    sprintf(n2.sname, "小红");
    n2.linknext = &n3;

    n3.num = 3;
    sprintf(n3.sname, "小芳");
    n3.linknext = &n4;

    n4.num = 4;
    sprintf(n4.sname, "小刚");
    n4.linknext = &n5;

    n5.num = 5;
    sprintf(n5.sname, "小志");
    n5.linknext = NULL;

    printf("
==========静态链表============
");

    //循环遍历----查询
    printf("
==========查询============
");
    for (head = &n1; head!= NULL; head = head->linknext)
    {
        printf("
num=%d,sname=%s,linknext=%x", head->num, head->sname, head->linknext);
    }


    //增加
    printf("
==========增加============
");
    struct LinkCode n6;
    n6.num = 6;
    sprintf(n6.sname, "小雨");

    struct LinkCode n7;
    n7.num = 7;
    sprintf(n7.sname, "小丽");

    //情景1，插入末尾
    printf("
==========增加到末尾============
");
    n5.linknext = &n6;
    n6.linknext = NULL;
    //循环遍历----查询
    for (head = &n1; head != NULL; head = head->linknext)
    {
        printf("
num=%d,sname=%s,linknext=%x", head->num, head->sname, head->linknext);
    }

    //情景2，插入到中间2后面
    printf("
==========增加到中间============
");
    struct LinkCode *px=NULL;
    for (head = &n1; head != NULL; head = head->linknext)
    {
        //注意for循环的执行顺序
        if (head->num==2)
        {
            px = head->linknext;
            head->linknext = &n7;
            n7.linknext = px;
        }
        printf("
num=%d,sname=%s,linknext=%x", head->num, head->sname, head->linknext);
    }

    //修改
    printf("
==========修改============
");
    //把小红的num修改成99
    for (head = &n1; head != NULL; head = head->linknext)
    {
        //strcmp()函数  串比较 str1>str2，返回值 > 0；两串相等，返回0
        if (!strcmp(head->sname,"小红"))
        {
            head->num = 99;
        }
        printf("
num=%d,sname=%s,linknext=%x", head->num, head->sname, head->linknext);
    }

    //删除
    printf("
==========删除============
");
    //删除num是7的节点
    for (head = &n1; head != NULL; head = head->linknext)
    {
        if (head->num==7)
        {
            //找到该节点的地址,再次重新开始循环遍历
            px = head;
        }
    }

    for (head = &n1; head != NULL; head = head->linknext)
    {
        if (head->linknext==px)
        {
            //找到要删除节点的上一个节点
            head->linknext = px->linknext;
        }
        printf("
num=%d,sname=%s,linknext=%x", head->num, head->sname, head->linknext);
    }


    printf("
");
}

//动态链表
void LinkTwo(){
    struct LinkCode * head, *p1, *p2, *p3, *p4, *p5;
    head = p1 = p2 = p3 = p4 = p5 = NULL;
    //先分配内存
    p1 = (struct LinkCode *)malloc(sizeof(struct LinkCode));
    p2 = (struct LinkCode *)malloc(sizeof(struct LinkCode));
    p3 = (struct LinkCode *)malloc(sizeof(struct LinkCode));
    p4 = (struct LinkCode *)malloc(sizeof(struct LinkCode));
    p5 = (struct LinkCode *)malloc(sizeof(struct LinkCode));

    p1->num = 1;
    sprintf(p1->sname, "小明1");
    p1->linknext = p2;

    p2->num = 2;
    sprintf(p2->sname, "小红1");
    p2->linknext = p3;

    p3->num = 3;
    sprintf(p3->sname, "小芳1");
    p3->linknext = p4;

    p4->num = 4;
    sprintf(p4->sname, "小刚1");
    p4->linknext = p5;

    p5->num = 5;
    sprintf(p5->sname, "小志1");
    p5->linknext = NULL;

    printf("
==========查询============
");
    //循环打印
    for (head = p1; head != NULL; head=head->linknext)
    {
        printf("
num=%d,sname=%s,linknext=%x", head->num, head->sname, head->linknext);
    }

    //增加
    printf("
==========增加============
");

    struct LinkCode *p6 = (struct LinkCode *)malloc(sizeof(struct LinkCode));
    struct LinkCode *p7 = (struct LinkCode *)malloc(sizeof(struct LinkCode));

    p6->num = 6;
    sprintf(p6->sname, "小雨1");
    p6->linknext = NULL;

    p7->num = 7;
    sprintf(p7->sname, "小丽1");
    p7->linknext = NULL;

    //情景1，在末尾追加
    p5->linknext = p6;
    printf("
==========增加(在末尾追加)============
");
    //循环打印
    for (head = p1; head != NULL; head = head->linknext)
    {
        printf("
num=%d,sname=%s,linknext=%x", head->num, head->sname, head->linknext);
    }

    printf("
==========增加(在中间追加)============
");
    struct LinkCode *py = NULL;
    //情景2，在中间追加(追加在小红后面)
    for (head = p1; head != NULL; head = head->linknext)
    {
        if (!strcmp(head->sname, "小红1"))
        {
            py = head->linknext;
            head->linknext = p7;
            p7->linknext = py;
        }
        printf("
num=%d,sname=%s,linknext=%x", head->num, head->sname, head->linknext);
    }

    //修改
    printf("
==========修改============
");
    p1->num = 99;
    for (head = p1; head != NULL; head = head->linknext)
    {
        printf("
num=%d,sname=%s,linknext=%x", head->num, head->sname, head->linknext);
    }

    //删除
    printf("
==========删除============
");
    //删除节点num=4的节点
    for (head = p1; head != NULL; head = head->linknext)
    {
        if (head->num==4)
        {
            //找到要删除的节点
            py = head;
        }
    }
    for (head = p1; head != NULL; head = head->linknext)
    {
        if (head->linknext==py)
        {
            head->linknext = py->linknext;
            free(py);
            //注意：动态链表的删除和静态链表的删除不同，静态链表创建是在栈中，而动态链表是用malloc()函数创建
            //所以动态链表在堆中，想要删除必须程序员手动用free()函数删除
        }
        printf("
num=%d,sname=%s,linknext=%x", head->num, head->sname, head->linknext);
    }

    printf("
");
}

//链表销毁
void ClearLink(){
    printf("
==========创建链表============
");
    struct LinkCode * head, *p1, *p2, *p3, *p4, *p5;
    head = p1 = p2 = p3 = p4 = p5 = NULL;
    //先分配内存
    p1 = (struct LinkCode *)malloc(sizeof(struct LinkCode));
    p2 = (struct LinkCode *)malloc(sizeof(struct LinkCode));
    p3 = (struct LinkCode *)malloc(sizeof(struct LinkCode));
    p4 = (struct LinkCode *)malloc(sizeof(struct LinkCode));
    p5 = (struct LinkCode *)malloc(sizeof(struct LinkCode));

    p1->num = 1;
    sprintf(p1->sname, "小明1");
    p1->linknext = p2;

    p2->num = 2;
    sprintf(p2->sname, "小红1");
    p2->linknext = p3;

    p3->num = 3;
    sprintf(p3->sname, "小芳1");
    p3->linknext = p4;

    p4->num = 4;
    sprintf(p4->sname, "小刚1");
    p4->linknext = p5;

    p5->num = 5;
    sprintf(p5->sname, "小志1");
    p5->linknext = NULL;

    printf("
==========查询============
");
    //循环打印
    for (head = p1; head != NULL; head = head->linknext)
    {
        printf("
num=%d,sname=%s,linknext=%x", head->num, head->sname, head->linknext);
    }

    //销毁链表(只要给我一个头结点的地址，我能够删除整个链表)
    printf("
==========销毁链表============
");
    //思路：一个个删除,保留第一个，删除第二个，把第三个重新连接成第二个
    struct LinkCode *pt = NULL;
    //循环打印
    while (p1->linknext!=NULL){
        //获取第二个的地址
        pt = p1->linknext;
        //把第三个的地址放到第一个后面
        p1->linknext = p1->linknext->linknext;
        //删除第二个
        free(pt);
    }
    //当p1->linknext!=NULL时，表示整个链表只剩下第一个了
    //循环打印
    for (head = p1; head != NULL; head = head->linknext)
    {
        printf("
num=%d,sname=%s,linknext=%x", head->num, head->sname, head->linknext);
    }
    //此时再删除第一个
    free(head);
    printf("
头结点的指针地址%x", head);
}

//链表逆转
void sort(){
    printf("
==========创建链表============
");
    struct LinkCode * head, *p1, *p2, *p3, *p4, *p5;
    head = p1 = p2 = p3 = p4 = p5 = NULL;
    //先分配内存
    p1 = (struct LinkCode *)malloc(sizeof(struct LinkCode));
    p2 = (struct LinkCode *)malloc(sizeof(struct LinkCode));
    p3 = (struct LinkCode *)malloc(sizeof(struct LinkCode));
    p4 = (struct LinkCode *)malloc(sizeof(struct LinkCode));
    p5 = (struct LinkCode *)malloc(sizeof(struct LinkCode));

    p1->num = 1;
    sprintf(p1->sname, "小明1");
    p1->linknext = p2;

    p2->num = 2;
    sprintf(p2->sname, "小红1");
    p2->linknext = p3;

    p3->num = 3;
    sprintf(p3->sname, "小芳1");
    p3->linknext = p4;

    p4->num = 4;
    sprintf(p4->sname, "小刚1");
    p4->linknext = p5;

    p5->num = 5;
    sprintf(p5->sname, "小志1");
    p5->linknext = NULL;

    printf("
==========查询============
");
    //循环打印
    for (head = p1; head != NULL; head = head->linknext)
    {
        printf("
num=%d,sname=%s,linknext=%x", head->num, head->sname, head->linknext);
    }

    //链表逆转(只给头结点的地址)
    printf("
==========链表逆转============
");
    //思路;存储第一个的地址，让第一个的下一个是NULL，第二个的下一个是原来的第一个，第三个下一个是原来的第二个
    head = p1;
    struct LinkCode *px = head;//头结点
    struct LinkCode *py = head->linknext;//第二个节点
    struct LinkCode *pz = NULL;
    while (py!=NULL){
        pz = py->linknext;//第三个节点
        //开始逆转
        py->linknext = px;//将第二个节点的下个节点赋值为第一个节点的地址
        //开始将所有指针向前移动1位
        px = py;//将第一个节点向前移动1位(移动到第二个节点的位置)
        py = pz;//将第二个节点向前移动1位(移动到第三个节点的位置)
        //此时再次进入循环 pz = py->linknext;   这会将第三个节点的值变成第四个节点
        //当py->linknext==NULL（即pz =NULL）的时候;表明此时py已经是链表最后一个节点了，
        //那么py->linknext的值就必须是链表倒数第二个的地址，所以还需要再循环1次，给py->linknext赋值，
        //再次经过py = pz;此时py==NULL;
    }
    //这个时候原来的第一个节点的linknext属性的值还是第二个节点的地址，，这是错误的，应该置为空
    head->linknext = NULL;
    //此时px就是原来链表最后一个节点的地址，因为head必须是头结点并且链表已经逆转了，
    //所以head的值不能是原来的第一个节点,而应该是原来链表最后一个节点的地址
    head = px;
    //循环打印
    for (head; head != NULL; head = head->linknext)
    {
        printf("
num=%d,sname=%s,linknext=%x", head->num, head->sname, head->linknext);
    }


}

//链表排序(方法1)
//方法1:交换2个元素的位置
//缺点：理解复杂，操作麻烦
//链表的冒泡排序与数组有巨大区别
//数组每个元素都可以单独确定,a[1]就是第二个元素
//但是链表他的每个元素都是由他的上一个元素确定，不存在有多少个元素的概念，只是上一次可以找到下一个
void Sort2(){
    printf("
==========创建链表============
");
    struct LinkCode * head, *p1, *p2, *p3, *p4, *p5;
    head = p1 = p2 = p3 = p4 = p5 = NULL;
    //先分配内存
    p1 = (struct LinkCode *)malloc(sizeof(struct LinkCode));
    p2 = (struct LinkCode *)malloc(sizeof(struct LinkCode));
    p3 = (struct LinkCode *)malloc(sizeof(struct LinkCode));
    p4 = (struct LinkCode *)malloc(sizeof(struct LinkCode));
    p5 = (struct LinkCode *)malloc(sizeof(struct LinkCode));

    p1->num = 30;
    sprintf(p1->sname, "小明1");
    p1->linknext = p2;

    p2->num = 12;
    sprintf(p2->sname, "小红1");
    p2->linknext = p3;

    p3->num = 9;
    sprintf(p3->sname, "小芳1");
    p3->linknext = p4;

    p4->num = 4;
    sprintf(p4->sname, "小刚1");
    p4->linknext = p5;

    p5->num = 2;
    sprintf(p5->sname, "小志1");
    p5->linknext = NULL;

    printf("
==========查询============
");
    //循环打印
    for (head = p1; head != NULL; head = head->linknext)
    {
        printf("
num=%d,sname=%s,linknext=%x", head->num, head->sname, head->linknext);
    }

    //链表排序(只给头结点的地址)---由小到大
    printf("
==========链表排序============
");
    //思路;定义3个变量，因为链表无法通过当前元素获取上一个元素，所以只能用一个变量将上一个变量的地址记录下来

    //px--代表第一个元素,py代表第二个元素，pz代表第三个元素
    //参与比较的是py与pz
    struct LinkCode * px, *py, *pz;
    //初始化指针，防止后面出错
    px = py = pz=NULL;
    //在比较链表前2个元素的时候，第一个元素没有上一个元素,所以px=py=head
    px =py= head=p1;

    
    //冒泡排序，每循环一次，会将一个最大值移动到末尾，每移动一次，需要移动的元素就会少一个
    //一共5个元素，移动4次后，最大的元素都已经放到链表末尾
    int index = 4;
    while (index){//外层循环
        //获取第三个元素的值
        pz = py->linknext;
        if (py->num>pz->num)
        {
            //如果第一个节点的num比第二个大，则要求交换位置
            //1.把第一个节点的下个节点属性赋值为第三个节点的地址
            //此时px是第一个元素
            px->linknext = pz;
            //2.把第二个节点的下个节点属性赋值为第四个节点的地址
            py->linknext = pz->linknext;
            //3.把第三个节点的下个节点属性赋值为第二个节点的地址
            pz->linknext = py;
            //第一组交换完成
            //4.将所有节点向前移动一位，这里px已经不是第一个元素了，他往前移动1位
            //因为要确定头结点的值，所以前2个元素的比较，必须单独提取出来
            head = px = pz;
        }
        do{
            pz = py->linknext;
            if (py->num>pz->num)
            {
                //如果第一个节点比第二个大，则要求交换位置
                //1.把第一个节点的下个节点属性赋值为第三个节点的地址
                px->linknext = pz;
                //2.把第二个节点的下个节点属性赋值为第四个节点的地址
                py->linknext = pz->linknext;
                //3.把第三个节点的下个节点属性赋值为第二个节点的地址
                pz->linknext = py;
                //第一组交换完成
                //4.将所有节点向前移动一位
                px = pz;
            }
            else{
                //如果大小顺序正确，3个元素都需要再向前移动1位；
                //把第二个元素赋值给原来第一个元素
                px = py;
                //把第三个元素赋值给原来第二个元素
                py = pz;
            }
        } while (py->linknext != NULL);//判断第三个元素是否是空
        //再次初始化
        //因为此时px,py,pz都已经移动到链表末尾
        px = py = head;
        pz = py->linknext;
        index--;
    }
    
    


    //循环打印
    for (head; head != NULL; head = head->linknext)
    {
        printf("
num=%d,sname=%s,linknext=%x", head->num, head->sname, head->linknext);
    }


}

//链表排序(方法2)
//方法1:交换2个元素的内容，不改变链表节点的位置，只是内容的交换
//优点：操作简单，通俗易懂
void Sort3(){
    printf("
==========创建链表============
");
    struct LinkCode * head, *p1, *p2, *p3, *p4, *p5;
    head = p1 = p2 = p3 = p4 = p5 = NULL;
    //先分配内存
    p1 = (struct LinkCode *)malloc(sizeof(struct LinkCode));
    p2 = (struct LinkCode *)malloc(sizeof(struct LinkCode));
    p3 = (struct LinkCode *)malloc(sizeof(struct LinkCode));
    p4 = (struct LinkCode *)malloc(sizeof(struct LinkCode));
    p5 = (struct LinkCode *)malloc(sizeof(struct LinkCode));

    p1->num = 3;
    sprintf(p1->sname, "小明1");
    p1->linknext = p2;

    p2->num = 12;
    sprintf(p2->sname, "小红1");
    p2->linknext = p3;

    p3->num = 9;
    sprintf(p3->sname, "小芳1");
    p3->linknext = p4;

    p4->num = 4;
    sprintf(p4->sname, "小刚1");
    p4->linknext = p5;

    p5->num = 2;
    sprintf(p5->sname, "小志1");
    p5->linknext = NULL;

    printf("
==========查询============
");
    //循环打印
    for (head = p1; head != NULL; head = head->linknext)
    {
        printf("
num=%d,sname=%s,linknext=%x", head->num, head->sname, head->linknext);
    }

    //链表排序(只给头结点的地址)---由小到大
    printf("
==========链表排序============
");

    struct LinkCode *px = NULL;
    struct LinkCode *py = NULL;
    struct LinkCode sz;

    for (px = head = p1; px != NULL; px = px->linknext)
    {
        for (py = head = p1; py != NULL; py = py->linknext)
        {
            //双循环
            //外循环的一个元素跟其他5个元素相比较，只要px<py就会发生交换
            //导致当2是最小元素的时候，他必须先跟前面比他大的所有元素，把自己变成最大，并非单单与最大元素进行交换
            //也就是小元素会不断的被推到最前面
            if (px->num<py->num)
            {
                sz.num = px->num;
                px->num = py->num;
                py->num = sz.num;

                sprintf(sz.sname, px->sname);
                sprintf(px->sname, py->sname);
                sprintf(py->sname, sz.sname);
            }
        }
    }
    //循环打印
    for (head = p1; head != NULL; head = head->linknext)
    {
        printf("
num=%d,sname=%s,linknext=%x", head->num, head->sname, head->linknext);
    }

}

void main(){
    //Linkone();
    //LinkTwo();
    //ClearLink();
    //sort();
    //Sort2();
    Sort3();

    system("pause");
}