数据结构（C语言）——单链表

整体结构如上：看似简单，但第一次用C语言实现还是感觉有点吃力，尤其是特别容易让链表断裂

下面是代码：（有链表的增删改查）

注：这里E类型是用define将int进行了宏定义

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

#define E int//以后想改元素类型就在这里该就行
typedef struct node {
	E element;//元素
	struct node* next;//下一节点的指针
}node;
void initialise_node(node* head) {
	head->next = NULL;//初始化头节点
}
int add_node(node* head,E ele,int index) {
	node* tem = head;//拷贝一份head，以后在tem上进行修改
	if (index < 1) return -1;//插入要位置大于0
	while (--index) {
		tem = tem->next;
		if (tem == NULL)return -1;
	}
	node* ptr = (node*)malloc(sizeof(node));
	ptr->next = NULL;
	if (ptr == NULL) {//开辟内存失败情况
		perror("malloc");
		return -1;
	}
	ptr->element = ele;
	ptr->next = tem->next;
	tem->next = ptr;
	return 1;
}
/// <summary>
/// 删除所有是ele的元素
/// </summary>
/// <param name="head">头节点指针</param>
/// <param name="ele">元素</param>
/// <returns></returns>
int del_node(node* head, E ele) {
	node* tem = NULL;
	while (1) {
		if (head->next == NULL) return 2;
		tem = head->next;//头节点移动
		if (tem->element == ele) {
			if (tem->next == NULL) {//找到的节点下一节点为空的情况
				free(tem);
				head->next = NULL;
				return 1;
			}
			head->next=tem->next;
			free(tem);
		}
		head = head->next;
	}
}
/// <summary>
/// 找出所有元素，并返回这个节点地址，如有需要返回多个可以创建一个数组
/// </summary>
/// <param name="head">头节点地址</param>
/// <param name="ele">要找的元素</param>
/// <returns></returns>
node* find_node(node* head, E ele) {
	head = head->next;//先让头节点移动一次
	while (head != NULL) {
		if (head->element == ele) {
			return head;
		}
		head = head->next;
	}
}
node* modify_node(node* head, int index, E ele) {
	head = head->next;//头节点指针先移动一次
	if (index < 1)return -1;
	while (--index && head != NULL) {
		head = head->next;
	}
	if (head == NULL)return -1;
	head->element = ele;
	return head;//返回这个元素的地址
}
//通过第几个数字找到元素
int del_node_byindex(node* head,int index) {
	node* tem = head->next;
	if (index < 1)return -1;
	while (--index && tem != NULL) {
		head = tem;
		tem = tem->next;//移动节点
	}
	if (tem == NULL)return -1;
	//删除节点
	head->next = tem->next;
	free(tem);
	tem = NULL;
}
void print_node(node* head) {
	node* tem = head;
	while (tem->next!=NULL) {
		tem = tem->next;
		printf("%d\n", tem->element);

	}
}
int main() {
	node head;
	initialise_node(&head);
	for (int i = 1; i <= 8; i++) {
		add_node(&head, 20 * i, i);
	}
	add_node(&head, 20, 9);
	printf("%d\n", del_node(&head, 20));
	node* find = find_node(&head, 160);
	printf("%d\n", find->element);
	printf("---------------\n");
	print_node(&head);
	printf("---------------\n");
	del_node_byindex(&head, 9);
	print_node(&head);
	printf("---------------\n");
	modify_node(&head, 3, 520);
	print_node(&head);
	return 0;
}