C语言链表创建与输出运行结果不正确

Question

#include <stdio.h>
#include <stdlib.h>
void addNode(int *data);
typedef struct LINKLIST
{
    int id;
    struct LINKLIST *next;
}L;
L *head=NULL,*tail=NULL;
int main()
{
    int n,val;
    L *head = (L*)malloc(sizeof(L)),*tail=NULL;
    head->next = NULL;
    tail = head;
    printf("Please input elements'num:\n");
    scanf("%d",&n);
    for (int i = 0; i < n; i++)
    {
        printf("number %d is:\n",i+1);
        scanf("%d",&val);
        addNode(&val);
    }
    printf("Linklist has been successfully created!\n");
    puts("Then output LinkList's data:\n");
    head = head->next;
    while (head!=NULL)
    {
        printf("%3d",head->id);
        head = head->next;
    }
    return 0;
}
void addNode(int *data)
{
    L *temp = (L*)malloc(sizeof(L));
    temp->id = *data;
    tail->next = temp;
    tail = temp;
    temp->next = NULL;
}

以上程序输入数字n->代表有链表n个节点
再通过for循环输入数据并赋值给val，使用addNode(&val);用于增加链表的节点。
但是输出结果未达到预期，能告诉我错在哪里吗？听劝！！
以下是运行结果：

Answer 1

你重定义了，在main函数里又重新定义head和tail，导致你开辟的空间什么的都没有给到全局变量

错的地方注释出来了

#include <stdio.h>
#include <stdlib.h>
void addNode(int *data);
typedef struct LINKLIST
{
    int id;
    struct LINKLIST *next;
}L;
L *head=NULL,*tail=NULL;
int main()
{
    int n,val;
    head = (L*)malloc(sizeof(L));//这里直接用就好了
    head->next = NULL;
    tail = head;
    printf("Please input elements'num:\n");
    scanf("%d",&n);
    for (int i = 0; i < n; i++)
    {
        printf("number %d is:\n",i+1);
        scanf("%d",&val);
        addNode(&val);
    }
    printf("Linklist has been successfully created!\n");
    puts("Then output LinkList's data:\n");
    head = head->next;
    while (head!=NULL)
    {
        printf("%3d",head->id);
        head = head->next;
    }
    return 0;
}
void addNode(int *data)
{
    L *temp = (L*)malloc(sizeof(L));
    temp->id = *data;
    tail->next = temp;
    tail = temp;
    temp->next = NULL;
}