学步园

郁闷！真心听不懂了！敲出代码也是错！百度知道无人解答！不管了，贴出来下午出去散散心！

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

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

PNODE create_list(void);
void traverse_list(PNODE pHead);
bool is_empty(PNODE pHead);
int length_list(PNODE);
bool insert_list(PNODE,int pos,int val);	//在pHead所指的链表的第pos个节点的前面插入一个新的节点，该节点的值是val,并且pos的值从1开始
bool delete_list(PNODE,int,int *);
void sort_list(PNODE pHead);	//排序
void main()
{
	PNODE pHead = NULL;	//等价于struct Node * pHead = NULL
	pHead = create_list();	//创建一个非循环链表，并将该链表的头地址赋给pHead
	traverse_list(pHead);
}
PNODE create_list(void)
{
	int len;
	int i;
	int val;	//用来临时存放用户输入的结点的值
	PNODE pHead = (PNODE)malloc(sizeof(NODE));
	if (NULL == pHead)
	{
		printf("分配失败，程序终止！\n");
		exit(-1);
	}
	PNODE pTail = pHead;
	pTail->pNext = NULL;
	printf("请输入您需要生成的链表节点个数：len:");
	scanf("%d",&len);
	for(i=0;i<len;len++)
	{
		printf("请输入第%d个链表节点的值",i+1);
		scanf("%d",&val);
		PNODE pNew = (PNODE)malloc(sizeof(NODE));
		if (NULL == pHead)
		{
		printf("分配失败，程序终止！\n");
		exit(-1);
		}
		pNew->data = val;
		pTail->pNext = pNew;
		pNew->pNext = NULL;
		pTail = pNew;
	}
	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)
{
	PNODE p= pHead->pNext;
	int len = 0;
	while (NULL !=p)
	{
		++len;
		p = p->pNext;
	}
	return len;
}
void sort_list(PNODE pHead)
{
	int i,j,t,len=0;
	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)	//类似于数组中的：a[i]>a[j]
			{
				t = p->data;//t = a[i];
				p->data = q->data;//a[i] = a[j];
				q->data = t;//a[j] = t;
			}
		}
	}
	return;
}
bool insert_list(PNODE,int pos,int val)
{
	int i = 0;
	PNODE p = pHead;
	while (NULL != p&& i<pos-1)
	{
		p = p->pNext;
		++i;
	}
	if (i>pos-1 ||NULL ==p)
		return false;
	PNODE pNew = (PNODE)malloc(sizeof(NODE));
	if (NULL ==pNew)
	{
		printf("动态内存分配失败！\n");
		exit(-1);
	}
	pNew->data = val;
	PNODE q = p->pNext;
	p->pNext = pNew;
	pNew->pNext = q;
	return true;
}
bool delete_list(PNODE,int pos,int * val)
{
	int i = 0;
	PNODE p = pHead;
	while (NULL != p&& i<pos-1)
	{
		p = p->pNext;
		++i;
	}
	if (i>pos-1 ||NULL ==p)
		return false;
	PNODE q = p->pNext;
	*pVal = q->data;
	//删除p节点后面的结点
	PNODE q = p->pNext->pNext;
	free(q);
	q = NULL;
	return true;
}