单向链表

#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
#include <stdlib.h>

struct node {
    int data;
    struct node* next;
};

int main() {
    struct node* head = NULL;
    struct node* current, * prev = NULL;

    // 创建链表并读取数据
    int i = 3;
    while (i--) {
        current = (struct node*)malloc(sizeof(struct node));
        if (current == NULL) {
            printf("内存分配失败。\n");
            exit(EXIT_FAILURE); // 如果内存分配失败，则退出程序
        }
        if (head == NULL)
            head = current;
        else
            prev->next = current;
        current->next = NULL;
        printf("请输入数据（int类型）:\n");
        scanf("%d", &current->data);
        prev = current;
    }

    // 打印链表
    current = head;
    while (current != NULL) {
        printf("当前数据为: %d \n", current->data);
        current = current->next;
    }

    // 尾部插入
    current = head;
    while (current->next != NULL) {
        current = current->next;
    }
    struct node* new_node = (struct node*)malloc(sizeof(struct node));
    if (new_node == NULL) {
        printf("内存分配失败。\n");
        exit(EXIT_FAILURE);
    }
    printf("请输入数据（int类型）:\n");
    scanf("%d", &new_node->data);
    new_node->next = NULL;
    current->next = new_node;

    // 打印更新后的链表
    current = head;
    while (current != NULL) {
        printf("当前数据为: %d \n", current->data);
        current = current->next;
    }

    // 中部插入
    printf("请输入你想在哪个数据的后面插入新的数据：\n");
    int num;
    scanf("%d", &num);
    current = head;
    while ((current->next != NULL) && (current->data != num)) {
        current = current->next;
    }
    struct node* news_node = (struct node*)malloc(sizeof(struct node));
    if (news_node == NULL) {
        printf("内存分配失败。\n");
        exit(EXIT_FAILURE);
    }
    printf("请输入数据（int类型）:\n");
    scanf("%d", &news_node->data);
    news_node->next = current->next;
    current->next = news_node;

    // 打印更新后的链表
    current = head;
    while (current != NULL) {
        printf("当前数据为: %d \n", current->data);
        current = current->next;
    }

    //头部插入
    current = head;
    struct node* newss_node = (struct node*)malloc(sizeof(struct node));
    if (newss_node == NULL) {
        printf("内存分配失败。\n");
        exit(EXIT_FAILURE);
    }
    printf("请输入数据（int类型）:\n");
    scanf("%d", &newss_node->data);
    newss_node->next = current;
    head = newss_node;

    // 打印更新后的链表
    current = head;
    while (current != NULL) {
        printf("当前数据为: %d \n", current->data);
        current = current->next;
    }
    // 删除数据
    printf("请输入想要删除的数据：\n");
    int nuum;
    scanf("%d", &nuum);

    // 特殊情况：如果要删除的是头节点
    if (head->data == nuum) {
        struct node* temp = head;
        head = head->next;
        free(temp);
    }
    else {
        current = head;
        // 遍历链表找到要删除的节点的前一个节点
        while (current->next != NULL && current->next->data != nuum) {
            current = current->next;
        }
        // 如果找到了要删除的节点
        if (current->next != NULL) {
            struct node* temp = current->next;
            current->next = current->next->next;
            free(temp);
        }
        // 如果未找到要删除的节点
        else {
            printf("要删除的数据在链表中不存在，请检查\n");
        }
    }

    // 打印更新后的链表
    current = head;
    while (current != NULL) {
        printf("当前数据为: %d \n", current->data);
        current = current->next;
    }

    // 释放malloc分配的内存
    current = head;
    while (current != NULL) {
        head = current->next;
        free(current);
        current = head;
    }
    return 0;
}