链表实验.

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

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

struct Node* initList() {
    struct Node* list = (struct Node*)malloc(sizeof(struct Node));
    list->data = 0;
    list->next = NULL;
    return list;
}

void headinsert(struct Node* list) {
    struct Node* tail = list;
    int num;
    printf("请输入整数序列（以0结束）：\n");

    while (1) {
        scanf("%d", &num);
        if (num == 0) {
            break;
        }
        struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));
        newNode->data = num;
        newNode->next = NULL;
        tail->next = newNode;
        tail = newNode;
    }
}

void printList(struct Node* head) {
    printf("链表的各个元素值为:\n");
    struct Node* current = head->next; // 跳过头节点
    while (current) {
        printf("%d ", current->data);
        current = current->next;
    }
    printf("\n");
}

int findPosition(struct Node* head, int x) {
    int position = 0;
    head = head->next;
    while (head != NULL) {
        position++;
        if (head->data == x) {
            return position;
        }
        head = head->next;
    }
    return 0;
}

void insertElement(struct Node* list, int i, int x) {
    struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));
    newNode->data = x;
    newNode->next = NULL;

    if (i <= 0) {
        newNode->next = list->next;
        list->next = newNode;
    }
    else {
        struct Node* current = list;
        int j = 0;
        while (current && j < i - 1) {
            current = current->next;
            j++;
        }
        if (current) {
            newNode->next = current->next;
            current->next = newNode;
        }
        else {
            printf("Error: Index out of range\n");
            free(newNode); // 释放新节点内存
        }
    }
}

int countnumber(struct Node* head, int x) {
    int count = 0;
    head = head->next;
    while (head != NULL) {
        if (head->data == x) {
            count++;
        }
        head = head->next;
    }
    return count;
}


int main() {
    struct Node* list = initList();
    headinsert(list);
    printList(list);

    int x = 0;
    printf("请输入要查找的元素的值:");
    scanf("%d", &x);
    int position = findPosition(list, x);
    if (position == 0) {
        printf("值为%d的元素不在链表中", x);
        printf("\n");
    }else{
        printf("值为%d的元素所在位置为%d", x, position);
        printf("\n");
    }

    int i = 0;
    int a = 0;
    printf("请输入要插入元素的值:");
    scanf("%d", &a);
    printf("请输入要插入元素的位置:");
    scanf("%d", &i);
    insertElement(list, i, a);
    printList(list);

    int b = 0;
    int number = 0;
    printf("请输入要查找元素个数的值:\n");
    scanf("%d", &b);
    number = countnumber(list, b);
    printf("值为%d的节点的个数为%d", b, number);

    return 0;
}