用C语言创建一个链表，并写出插入和删除的函数

好的，下面是用C语言创建链表的代码：

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

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

struct node *head = NULL;

void insert(int data) {
    struct node *new_node = (struct node*) malloc(sizeof(struct node));
    new_node->data = data;
    new_node->next = head;
    head = new_node;
}

void delete(int data) {
    struct node *current = head;
    struct node *previous = NULL;

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

    if (current == NULL) {
        printf("Element not found.\n");
        return;
    }

    if (previous == NULL) {
        head = current->next;
    } else {
        previous->next = current->next;
    }

    free(current);
}

int main() {
    insert(1);
    insert(2);
    insert(3);
    insert(4);

    delete(3);

    struct node *current = head;
    while (current != NULL) {
        printf("%d ", current->data);
        current = current->next;
    }

    return 0;
}

这个程序创建了一个链表，并实现了插入和删除函数。插入函数将新节点插入到链表的头部，而删除函数根据给定的数据删除链表中的节点。