数据结构之单链表

数据结构就是存储数据的不同方式。

数据与数据之间的关系 
  
    数据的逻辑结构：数据元素与元素之间的关系
       集合：关系平等
   线性结构：元素之间一对一的关系（表（数组，链表），队列。栈。。。）
   树型结构：元素之间一对多的关系（二叉树）
   图形结构：元素之间多对多的关系（网状结构）
 

单链表：链表的头插、尾插、头删尾删、查找、更改、销毁

/*************************************************************************
	> File Name: link.c
	> Author: yas
	> Mail: rage_yas@hotmail.com
	> Created Time: Mon 18 Mar 2024 01:42:51 PM CST
 ************************************************************************/
#include "link.h"
#include<stdio.h>
link_list *create_head_link(void)
{
    link_list *head = NULL;

    head = malloc(sizeof(link_list));
    if (head == NULL)
    {
        perror("fail to malloc");
        return NULL;
    }

    head->phead = NULL;
    head->clen = 0;

    return head;
}
/* 头插 */
int push_head_node(link_list *plist, DATA_TYPE data)
{
    link_node *pnode = NULL;
    pnode = malloc(sizeof(link_node));
    if (pnode == NULL)
    {
        perror("fail to malloc");
        return -1;
    }

    pnode->data = data;
    pnode->pnext = NULL;
    
    pnode->pnext = plist->phead;
    plist->phead = pnode;

    plist->clen++;

    return 0;
}

/* 尾插 */
int push_tail_node(link_list *plist, DATA_TYPE data)
{
    link_node *pnode = NULL;

    pnode = malloc(sizeof(link_node));
    if (pnode == NULL)
    {
        perror("fail to malloc");
        return -1;
    }
    
    pnode->pnext = NULL;
    pnode->data = data;

    if (plist->phead == NULL)
    {
        plist->phead = pnode;
    }
    else
    {
        link_node *ptmp = NULL;
        ptmp = plist->phead;

        while(ptmp->pnext != NULL)
        {
            ptmp = ptmp->pnext;
        }

        ptmp->pnext = pnode;
        
    }

    plist->clen++;
    return 0;
}
/* 尾删 */
int pop_tail_node(link_list *plist)
{
    link_node *ptmp = plist->phead;
    
    if(plist->phead == NULL)    //空链表
    {
        return 0;
    }

    else if (NULL == ptmp->pnext)
    {
        free(ptmp);
        plist->phead = NULL;
    }
    else
    {
        while(ptmp->pnext->pnext != NULL)
        {
            ptmp = ptmp->pnext;
        }

        free(ptmp->pnext);      //释放尾节点
        ptmp->pnext = NULL;     //新的尾节点
    }

    plist->clen--;

    return 0;
}
/* 头删 */
int pop_head_node(link_list *plist)
{
    link_node *ptmp = plist->phead;
    if(plist->phead == NULL)    //空链表
    {
        return 0;
    }

    else if (NULL == ptmp->pnext)
    {
        free(ptmp);
        plist->phead = NULL;
    }
    else
    {
        plist->phead = ptmp->pnext;
        free(ptmp);
    }

    plist->clen--;
    return 0;
}

/* 查找链表第一个相同的数的地址 */
link_node *find_local(link_list *plist, DATA_TYPE data)
{
    link_node *ptmp = plist->phead;
    while(ptmp->pnext != NULL)
    {
        if(ptmp->data != data)
        {
            ptmp = ptmp->pnext;
        }
        else if(ptmp->data == data)
        {
            return ptmp;
        }
    }

    return NULL;
    
}
/* 更改链表数据 */
int change_link(link_list *plist, DATA_TYPE olddata, DATA_TYPE newdata)
{
    link_node *ptmp = NULL;
    ptmp = find_local(plist, olddata);
    if (ptmp == NULL)
    {
        return -1;
    }
    ptmp->data = newdata;

    return 0;
}

/* 销毁 */
int destroy_link(link_list *plist)
{

    while(plist->clen != 0)
    {
        pop_tail_node(plist);
    }

    return 0;
}