单链表的C语言算法实现

自己用C语言实现的单链表算法，有什么不正确的地方，请各位共同讨论与指正。

#include <stdio.h>#include <stdlib.h>#include <malloc.h>typedef struct Node{    int data;               //结点数据域    struct Node *pNext;    //指向下一结点的指针域}NODE, *PNODE;//创建一个链表PNODE create_list(void){    PNODE pHead;    //链表头指针    PNODE pTail;    //链表尾指针    int length;     //链表有效结点个数    int i;    int val;        //每个结点的数据域    PNODE pNew;     //指向新创建的结点    printf("请输入要创建链表结点的个数：length= ");    scanf("%d", &length);    pHead = (PNODE)malloc(sizeof(NODE));        //创建头结点    if (pHead == NULL)    {        printf("内存分配失败，程序将终止!\n");        exit(-1);    }    pHead->pNext = NULL;    pTail = pHead;              //链表有效结点为零时，尾结点相当于头结点    for (i=0; i<length; i++)    {        printf("请输入第%d个结点的值：", i+1);        scanf("%d", &val);        pNew = (PNODE)malloc(sizeof(NODE));     //为新结点分配内存        if (pNew == NULL)        {            printf("内存分配失败，程序将终止!\n");            exit(-1);        }        pNew->data = val;        pTail->pNext = pNew;        //使尾结点的指针域指向新创建的结点        pNew->pNext = NULL;         //使新创建结点的指针域指向NULL        pTail = pNew;               //把新创建的结点变成尾结点    }    return pHead;}//遍历整个链表void traverse_list(PNODE pHead){    PNODE p = pHead->pNext;    while (p != NULL)    {        printf("%d ", p->data);        p = p->pNext;    }    printf("\n");    return;}//判断链表是否为空int is_empty(PNODE pHead){    if (pHead->pNext == NULL)    {        return 0;    }    else    {        return -1;    }}//求链表的长度int length_list(PNODE pHead){    int length = 0;    PNODE p = pHead->pNext;    while (p != NULL)    {        length++;        p = p->pNext;    }    return length;}//排序void sort_list(PNODE pHead){    int i, j, t, len = length_list(pHead);    PNODE p, q;    p = pHead;    for (i=0; i<len-1; i++)    {        p = p->pNext;        q = p->pNext;        for (j=i+1; j<len; j++)        {            if (p->data > q->data)            {                t = p->data;                p->data = q->data;                q->data = t;            }            q = q->pNext;        }    }}//在第pos个结点之前插入一个结点valint insert_list(PNODE pHead, int pos, int val){    PNODE p = pHead;    int i=0;    while (p != NULL && i < pos - 1)    {        p = p->pNext;        i++;            //找到第i个结点    }    if (p == NULL || i > pos - 1)    {        return -1;    }    PNODE pNew = (PNODE)malloc(sizeof(NODE));    if (pNew == NULL)    {        printf("内存分配失败，程序将终止!\n");        exit(-1);    }    pNew->data = val;    pNew->pNext = p->pNext;    p->pNext = pNew;    return 0;}//删除第pos个结点int delete_list(PNODE pHead, int pos, int *pVal){    PNODE p = pHead;    int i=0;    //找到待删结点的前一个结点    while (p->pNext != NULL && i < pos - 1)    {        p = p->pNext;        i++;    }    if (p->pNext == NULL || i > pos - 1)    {        return -1;    }    *pVal = p->pNext->data;    PNODE q = p->pNext;    p->pNext = p->pNext->pNext;    free(q);    return 0;}int main(){    int val;    PNODE pHead = create_list();    traverse_list(pHead);    if (delete_list(pHead, 3, &val) == 0)    {        printf("删除成功，您删除的元素是：%d\n", val);    }    else    {        printf("删除失败\n");    }    traverse_list(pHead);    return 0;}