数据结构---链表

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

typedef struct Node
{
    int data; //数据域
    struct Node * pNext;//指针域
}NODE,*PNODE;

//函数声明
PNODE creat_list(void);
void traverse_list(PNODE pHead);
bool is_empty(PNODE pHead);
int length_list(PNODE pHead);
bool insert_list(PNODE ,int,int);
bool delete_list(PNODE,int,int *);//  int*表示删除的数字
void sort_list(PNODE);


int main (void)
{
    PNODE pHead = NULL; 
    int val;

    pHead = creat_list();//创建一个非循环单链表 ，并将该链表的头结点的地址付给pHead;
    traverse_list(pHead);
    insert_list(pHead,4,33);
    traverse_list(pHead);
    delete_list(pHead,5,&val);
    traverse_list(pHead);
    printf("删除的是%d\n",val);

    /*
    sort_list(pHead);
    traverse_list(pHead);
    int len = length_list(pHead);
    printf("链表的长度是：%d\n", len);
    /*    if(is_empty(pHead))
        printf("链表为空！");
    else
        printf("链表不空！");*/

    return 0;
}

PNODE creat_list(void)
{
    int len;
    int i;
    int val;//临时存放用户输入结点的值
    PNODE pHead = (PNODE)malloc(sizeof(NODE));//pHead是指向头节点的指针，指向的是头节点
    if(NULL==pHead)
    {    
        printf("分配内存失败！\n");
        exit(-1);
    }
    PNODE pTail = pHead;
    pTail ->pNext = NULL;

    printf("请输入您需要生成的链表结点的个数:LEN=");
    scanf("%d",&len);
    for(i = 0;i<len;i++)
    {
        printf("请输入第%d个结点的值：",i+1);
        scanf("%d",&val);
        PNODE pNew  = (PNODE)malloc(sizeof(NODE));
        if(NULL==pNew)
        {    
            printf("分配内存失败！\n");
            exit(-1);
        }
        pNew->data = val;
        pTail->pNext = pNew;
        pNew->pNext = NULL;
        pTail = pNew;//pTail往后挪一位

    }
    return pHead;
}

void traverse_list(PNODE pHead)
{
    PNODE p = pHead->pNext;
    while(NULL!=p)
    {
        printf("%d ",p->data);
        p = p->pNext;
    }
    printf("\n");
    return;
}
bool is_empty(PNODE pHead)
{
    if(NULL==pHead->pNext)
        return true;
    else return false;
}
int length_list(PNODE pHead)
{
    int len = 0;
    PNODE p = pHead->pNext;
    while(NULL!=p)
    {
        len++;
        p = p->pNext;
    }
    return len;
}

void sort_list(PNODE pHead)
{
    int i,j,t;
    int len = length_list(pHead);
    PNODE p,q;

    for(i=0, p = pHead->pNext;i<len-1; ++i,p=p->pNext)
    {
        for(j= i+1,q = p->pNext; j<len;++j, q = q->pNext)
        {
            if(p->data>q->data)
            {
                t = p->data;
                p->data  = q->data;
                q->data = t;
            }
        }
    }
    return;
}

//在pos前的位置上插入
bool insert_list(PNODE pHead ,int pos,int val)
{
    PNODE p = pHead;
    int i = 0;
    //循环的结果是   p到了pos的前一个指针位置
    for(i = 0; i<pos-1 ;i++)
    {
        p = p->pNext;
    }
    if(pos<0 ||p == NULL)
    {
        return false;
    }
    PNODE pNew = (PNODE)malloc(sizeof(NODE));
    if(pNew ==NULL)
    {
        printf("申请内存失败！\n");
        exit(-1);
    }
    pNew->data = val;
    pNew->pNext = p->pNext;
    p->pNext = pNew;
    return true;
}

bool delete_list(PNODE pHead,int pos,int *val)
{
    PNODE p = pHead;
    int i = 0;

    for(i = 0; i<pos-1 ;i++)
    {
        if(P==NULL)
        {
            break;
        }
        p = p->pNext;
    }
    if(pos<0||p->pNext ==NULL)
    {
        *val = 0;
        return false;
    }
    PNODE q = p->pNext;
    p->pNext = p->pNext->pNext;
    *val = q->data;
    free(q);
    q = NULL;
    return true;
}