单向链表 增 删 改 查

#include <stdio.h>#include <malloc.h>typedef struct node {	int num;	node* next;} NODE;int lenght = -1;//线性表的链式结构的长度/*    创建节点 */NODE* create_node(int num) {	NODE* n = (NODE*) malloc(sizeof(NODE));	n->num = num;	n->next = NULL;	lenght++;	return n;}/*    插入一个结点到某个数字的后面    return 插入是否成功*/int insert_node(NODE* head, int how, int num) {	NODE* p = head->next;	while (p != NULL) {		if (p->num == how) {			NODE* z = p->next;			p->next = create_node(num);			p->next->next = z;			return 1;		}		p = p->next;	}	return 0;}/*    删除一个结点*/int delete_node(NODE* head, int how) {	NODE* p = head->next;	NODE* last = head;	while (p != NULL) {		if (p->num == how) {			last->next = p->next;			free(p);			p = NULL;			lenght--;			return 1;		}		p = p->next;		last = last->next;	}	return 0;}/*    修改一个结点*/void update_node(NODE* head, int how, int num) {	NODE* p = head->next;	while (p != NULL) {		if (p->num == how) {			p->num = num;			return;		}		p = p->next;	}	PRintf("该元素不存在！/n");}/*    查询一个节点*/void search_node(NODE* head, int how) {	NODE* p = head->next;	while (p != NULL) {		if (how == p->num) {			printf("查询到 %d/n", p->num);			return;		}		p = p->next;	}	printf("该元素不存在！/n");}void print_list(NODE* head) {  //线性表的链式结构的遍历	NODE* p = head;	while (p != NULL) {		printf("%d ", p->num);		p = p->next;	}	printf("/n/n");}int main() {	NODE* headNode = create_node(-1);  //创建头结点	NODE* p = headNode;	for (int i = 0; i < 10; i++) {		p->next = create_node(i);		if (headNode->next == NULL) {			printf("NULL");		}		p = p->next;	}	printf("线性表的链式结构的长度 = %d/n", lenght);	print_list(headNode->next);	printf("--插入数据：100/n");	insert_node(headNode, 4, 100); //在数字4的后面插入100 	printf("线性表的链式结构的长度 = %d/n", lenght);	print_list(headNode->next);	printf("--删除数据：0/n");	delete_node(headNode, 0);  //删除数字为0的节点	printf("线性表的链式结构的长度 = %d/n", lenght);	print_list(headNode->next);	printf("--修改数据：1/n");	update_node(headNode, 1, 111); //修改数字1为111	printf("线性表的链式结构的长度 = %d/n", lenght);	print_list(headNode->next);		printf("--查询数据：1000/n");	search_node(headNode, 1000); //查询1000是否存在于链表当中  	return 0;}