链表后续完善（一）

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

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

PNODE createList();                //创建链表
void traverseList(PNODE pHead);    //遍历
bool isEmpty(PNODE pHead);        //判断链表是否为空
int getLength(PNODE pHead);        //取得链表长度
bool insertList(PNODE pHead);    //插入元素
bool deleteList(PNODE pHead, int * pVal );    //删除元素
void sortList(PNODE pHead);        //排序

int main()
{

    PNODE pHead = NULL;        //等价于struct Node * pHead = NULL;
    pHead = createList();    //createList()函数功能：创建一个非循环单链表
                            //并将该链表的头节点的地址赋给pHead
   /*                      
    if(insertList(pHead)){
    printf("插入成功！\n");
    }else{
     printf("插入失败！\n");
    }
    
        
   // sortList(pHead);
    */

    int val;
    if(deleteList(pHead, &val)){
        printf("删除成功！\n");
        printf("删除的元素是%d\n", val);
    }else{
        printf("删除失败！\n");
    }
    
    traverseList(pHead);    
    
    if(isEmpty(pHead)){
        printf("链表为空！\n");
    }else{
        printf("链表不空！\n");    
    }
   
    
    printf("链表的长度为：%d！\n", getLength(pHead));    
    
    system("pause");
    return 0;
}

PNODE createList(void){
    int len;    //用来存放有效节点的个数
    int i;
    int val;    //用来临时存放用户输入的节点的值
    
    //分配了一个不存放有效数据的头节点
    PNODE pHead = (PNODE)malloc(sizeof(NODE));
    if(NULL == pHead){
        printf("分配失败！\n");
        exit(-1);
    }
    
    //创建一个永远指向尾节点的指针
    PNODE pTail = pHead;    
    pTail->pNext = NULL;        
    
    printf("请输入您需要生成的链表节点的个数：len = ");
    scanf("%d", &len);

    
    for(i = 0; i < len; ++i){
        printf("请输入第%d个节点的值：", i+1);
        scanf("%d", &val);
        
        PNODE pNew  = (PNODE)malloc(sizeof(NODE));
        if(NULL == pNew){
        printf("分配失败！\n");
        exit(-1);
        }
        pNew->data = val;
        pTail->pNext = pNew;
        pNew->pNext = NULL;
        pTail = pNew;
        
    }
    return pHead;
} 

void traverseList(PNODE pHead){
    PNODE p = pHead->pNext;
    
    while(p != NULL){
        printf("%d   ", p->data);
        p = p->pNext;
    }
    
    printf("\n");
}

bool isEmpty(PNODE pHead){
    if(NULL == pHead->pNext)
        return true;
    else
        return false;
}

int getLength(PNODE pHead){
    PNODE p = pHead->pNext;
    int len  = 0;
    
    while(NULL != p){
        ++len;
        p = p->pNext;
    }
    return len;
}

//在pHead所指向链表的第POS个节点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 insertList(PNODE pHead){
    
    int i = 0;
    int pos, val;
    printf("请输入您要插入的位置：pos = ");
    scanf("%d", &pos);
    
    printf("请输入您要插入的数据：val = ");
    scanf("%d", &val);
    
    PNODE p = pHead;
    while(NULL != p && i < pos-1){
        p = p->pNext;
        ++i;
    }
    
    //判断POS的位置是否合法
    if(i>pos-1 || NULL == p)
        return false;
    PNODE pNew = (PNODE)malloc(sizeof(NODE));
    if(NULL == pNew){
        printf("动态分配内存失败！\n");
        exit(-1);
    }    
    pNew->data = val;
    pNew->pNext = p->pNext;
    p->pNext = pNew;
   
   
    return true;
   
}
    
void sortList(PNODE pHead){
    int i, j, t;
    int len = getLength(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;
            }
        }
    }
}

bool deleteList(PNODE pHead, int * pVal ){
    int i = 0;    
    int pos;
    printf("请输入您要删除的位置：pos = ");
    scanf("%d", &pos);
    
    PNODE p = pHead;
    while(NULL != p->pNext && i < pos-1){
        p = p->pNext;
        ++i;
    }
    //判断POS的位置是否合法
    if(i>pos-1 || NULL == p->pNext)
        return false;
   
    PNODE q = p->pNext;

    *pVal = q->data;
    //删除p节点后面的节点
    p->pNext = q->pNext;
    free(q);
    q = NULL;

    return true;
    
}