用c语言写一个程序，用数据结构建链表，要求输入一个数，如果链表有这个数，就删除这个数，没有就在链表最后加上这个数

在C语言中，我们可以创建一个单向链表来实现这个功能。首先，我们需要定义一个节点结构体，然后编写一个函数来创建链表、插入元素和删除元素。下面是一个简单的实现：

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

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

// 创建新节点
Node* createNode(int data) {
    Node* newNode = (Node*) malloc(sizeof(Node));
    newNode->data = data;
    newNode->next = NULL;
    return newNode;
}

// 添加元素到链表末尾
void append(Node** head, int data) {
    Node* newNode = createNode(data);

    if (*head == NULL) {
        *head = newNode;
        return;
    }

    Node* last = *head;
    while (last->next != NULL) {
        last = last->next;
    }
    last->next = newNode;
}

// 查找并删除元素
void deleteElement(Node** head, int data) {
    Node* current = *head;
    Node* previous = NULL;

    if (current != NULL && current->data == data) {
        *head = current->next;
        free(current);
        return;
    }

    while (current != NULL && current->data != data) {
        previous = current;
        current = current->next;
    }

    if (current != NULL) {
        previous->next = current->next;
        free(current);
    }
}

// 打印链表
void printList(Node* head) {
    Node* temp = head;
    while (temp != NULL) {
        printf("%d -> ", temp->data);
        temp = temp->next;
    }
    printf("NULL\n");
}

int main() {
    Node* head = NULL;
    
    int choice, num;
    do {
        printf("\n1. Insert\n2. Delete\n3. Exit\nChoose an operation: ");
        scanf("%d", &choice);

        switch(choice) {
            case 1:
                printf("Enter a number to add: ");
                scanf("%d", &num);
                append(&head, num);
                break;
            case 2:
                printf("Enter a number to delete: ");
                scanf("%d", &num);
                deleteElement(&head, num);
                break;
            case 3:
                printf("Exiting...\n");
                break;
            default:
                printf("Invalid choice. Try again.\n");
                break;
        }

    } while (choice != 3);

    printf("Final linked list:\n");
    printList(head);
    return 0;
}