增删改查有序链表

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

// 定义链表节点结构体
typedef struct Node {
    int data;
    struct Node* next;
} Node;

// 头指针（全局变量）
Node* head = NULL;

插入

void insertSorted(int value) {
    Node* newNode = (Node*)malloc(sizeof(Node));
    if (!newNode) {
        printf("内存分配失败！\n");
        exit(1);
    }
    newNode->data = value;
    newNode->next = NULL;

    // 情况1：链表为空或新值小于等于头节点
    if (head == NULL || value <= head->data) {
        newNode->next = head;
        head = newNode;
        return;
    }

    // 情况2：寻找插入位置
    Node* current = head;
    while (current->next != NULL && current->next->data < value) {
        current = current->next;
    }
    newNode->next = current->next;
    current->next = newNode;
}

删

void deleteNode(int value) {
    if (head == NULL) {
        printf("链表为空！\n");
        return;
    }

    // 处理头节点是要删除的节点的情况
    if (head->data == value) {
        Node* temp = head;
        head = head->next;
        free(temp);
        return;
    }

    Node* current = head;
    while (current->next != NULL && current->next->data != value) {
        current = current->next;
    }

    if (current->next == NULL) {
        printf("未找到值为 %d 的节点！\n", value);
        return;
    }

    // 找到目标节点并删除
    Node* temp = current->next;
    current->next = temp->next;
    free(temp);
}

改

void updateNode(int oldValue, int newValue) {
    Node* target = searchNode(oldValue);
    if (target == NULL) {
        printf("未找到值为 %d 的节点！\n", oldValue);
        return;
    }
    target->data = newValue;
    printf("已将 %d 修改为 %d\n", oldValue, newValue);
}

查

Node* searchNode(int value) {
    Node* current = head;
    while (current != NULL) {
        if (current->data == value) {
            return current; // 返回找到的节点指针
        }
        current = current->next;
    }
    return NULL; // 未找到
}

打印链表

void printList() {
    Node* current = head;
    printf("链表内容：");
    while (current != NULL) {
        printf("%d -> ", current->data);
        current = current->next;
    }
    printf("NULL\n");
}

完整测试代码

int main() {
    // 初始化链表
    head = NULL;

    // 插入测试
    insertSorted(5);
    insertSorted(3);
    insertSorted(7);
    insertSorted(1);
    insertSorted(9);
    printList(); // 输出: 1 -> 3 -> 5 -> 7 -> 9 -> NULL

    // 查找测试
    Node* found = searchNode(5);
    if (found) {
        printf("找到值为 5 的节点。\n");
    } else {
        printf("未找到值为 5 的节点。\n");
    }

    // 修改测试
    updateNode(5, 6);
    printList(); // 输出: 1 -> 3 -> 6 -> 7 -> 9 -> NULL

    // 删除测试
    deleteNode(3);
    printList(); // 输出: 1 -> 6 -> 7 -> 9 -> NULL

    // 删除不存在的节点
    deleteNode(10); // 输出: 未找到值为 10 的节点！

    // 清空链表
    while (head != NULL) {
        deleteNode(head->data);
    }
    printList(); // 输出: 链表内容：NULL

    return 0;
}