继续

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

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

void createList(struct Node **head) {
    *head = (struct Node *)malloc(sizeof(struct Node));
    (*head)->next = NULL;

    printf("请输入20个整数：\n");
    struct Node *p = *head;
    for (int i = 1; i <= 20; i++) {
        struct Node *newNode = (struct Node *)malloc(sizeof(struct Node));
        scanf("%d", &newNode->data);
        newNode->next = NULL;

        p->next = newNode;
        p = newNode;
    }

    printf("单链表的结点值为：");
    struct Node *q = (*head)->next;
    while (q != NULL) {
        printf("%d ", q->data);
        q = q->next;
    }
    printf("\n");
}

void searchNode(struct Node *head) {
    int x;
    printf("请输入要查找的整数：");
    scanf("%d", &x);

    struct Node *p = head->next;
    while (p != NULL) {
        if (p->data == x) {
            printf("找到了\n");
            return;
        }
        p = p->next;
    }

    printf("找不到\n");
}

void insertNode(struct Node *head) {
    int i, x;
    printf("请输入要插入的位置和数值（用空格隔开）：");
    scanf("%d %d", &i, &x);

    struct Node *p = head;
    for (int j = 1; j < i && p != NULL; j++) {
        p = p->next;
    }
    if (p == NULL) {
        printf("插入位置不合法\n");
        return;
    }

    struct Node *newNode = (struct Node *)malloc(sizeof(struct Node));
    newNode->data = x;
    newNode->next = p->next;
    p->next = newNode;

    printf("单链表的结点值为：");
    struct Node *q = head->next;
    while (q != NULL) {
        printf("%d ", q->data);
        q = q->next;
    }
    printf("\n");
}

void deleteNode(struct Node *head) {
    int i;
    printf("请输入要删除的位置：");
    scanf("%d", &i);

    struct Node *p = head;
    for (int j = 1; j < i && p != NULL; j++) {
        p = p->next;
    }
    if (p == NULL || p->next == NULL) {
        printf("删除位置不合法\n");
        return;
    }

    struct Node *q = p->next;
    p->next = q->next;
    free(q);

    printf("单链表的结点值为：");
    struct Node *r = head->next;
    while (r != NULL) {
        printf("%d ", r->data);
        r = r->next;
    }
    printf("\n");
}

int main() {
    struct Node *head = NULL;
    createList(&head);

    int choice;
    do {
        printf("请选择操作：\n");
        printf("1. 查找结点\n");
        printf("2. 插入结点\n");
        printf("3. 删除结点\n");
        printf("4. 退出程序\n");
        scanf("%d", &choice);

        switch (choice) {
            case 1:
                searchNode(head);
                break;
            case 2:
                insertNode(head);
                break;
            case 3:
                deleteNode(head);
                break;
            case 4:
                break;
            default:
                printf("输入有误，请重新选择\n");
                break;
        }
    } while (choice != 4);

    return 0;
}

注意，这段代码中的单链表是带表头的，即第一个结点不存储数据，只作为头结点使用。同时，这段代码中的单链表是静态创建的，即在程序运行期间无法动态添加或删除结点，如果需要实现动态添加或删除结点，需要进行相应的修改。