数据结构入门——链表的实现

    该程序实现了链表的增、删、遍历、排序等大部分功能，仅供参考。理解链表的原理，对后面栈、队列、二叉树、图等数据结构的学习有很大帮助。

链表的实现：

# include <stdio.h># include <malloc.h># include <stdlib.h>typedef struct Node{int data;struct Node * pNext;}NODE, *PNODE;PNODE create_list(void);void traverse_list(const PNODE);bool is_empty(PNODE);int length_list(PNODE);bool sort_list(PNODE);bool insert_list(PNODE);bool delete_list(PNODE);int main(void){PNODE pHead = (PNODE)malloc(sizeof(NODE));pHead = create_list();traverse_list(pHead);is_empty(pHead);int len = length_list(pHead);printf("链表的长度为：%d\n", len);printf("排序后：\n");sort_list(pHead);traverse_list(pHead);insert_list(pHead);traverse_list(pHead);delete_list(pHead);traverse_list(pHead);return 0;}PNODE create_list(void){int i;int val;int len;PNODE pHead = (PNODE)malloc(sizeof(NODE));PNODE pTail = pHead;pTail->pNext = NULL;printf("请输入节点的个数：len = ");scanf("%d", &len);for (i=0; i<len; ++i){printf("请输入第%d个节点数据: val = ", i+1);scanf("%d", &val);PNODE pNew = (PNODE)malloc(sizeof(NODE));if (NULL == pNew){printf("内存空间分配失败！\n");exit(-1);}pNew->data = val;pTail->pNext = pNew;pNew->pNext = NULL;pTail = pNew;}return pHead;}void traverse_list(const PNODE pHead){PNODE p = pHead->pNext;if(NULL == p){printf("链表为空！\n");return;}printf("\n链表中的数据为：\n");while (NULL != p){printf("%d  ", p->data);p = p->pNext;}printf("\n");return;}bool is_empty(PNODE pHead){PNODE p = pHead;if(NULL == p->pNext){return true;}else{return false;}}int length_list(PNODE pHead){int len = 0;PNODE p = pHead;while (NULL != p->pNext){++len;p = p->pNext;}return len;}bool sort_list(PNODE pHead){int i, j;int t;int len;PNODE p, q;if ( is_empty(pHead) ){printf("链表为空！\n");return false;}else{len = length_list(pHead);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 true;}}bool insert_list(PNODE pHead){int i = 0;int pos, val;PNODE p = pHead;printf("请输入您要插入的位置：pos = ");scanf("%d", &pos);//判断输入位置pos的正确性并使指针后移，使指针p指向最后一个结点。此语句非常经典！while (NULL!=p && i<pos-1){p = p->pNext;++i;}if (i>pos-1 || NULL==p)  //判断位置的正确性及指针p的是否为空，防止程序崩溃。{printf("输入错误，插入失败！\n");return false;}printf("请输入您要插入的数据：val = ");scanf("%d", &val);PNODE pNew = (PNODE)malloc(sizeof(NODE));if (NULL == pNew){printf("内存分配失败！\n");exit(-1);}pNew->data = val;pNew->pNext = p->pNext;p->pNext = pNew;return true;}bool delete_list(PNODE pHead){int i = 0;int pos, val;PNODE p = pHead;printf("请输入您要删除的位置：pos = ");scanf("%d", &pos);while (NULL!=p->pNext && i<pos-1){p = p->pNext;++i;}if (NULL==p->pNext || i>pos-1){printf("输入错误，删除失败！\n");return false;}PNODE q = p->pNext;val = q->data;//删除p后面的结点p->pNext = p->pNext->pNext;free(q);q = NULL;printf("删除成功，您删除的数据为：%d", val);}