我的链接列表的清晰度

Question

我正在尝试实现一个链接列表。我对这段代码有问题。比如说，我想创建一个应该有 3 个项目的列表，项目为 45、56、67。我得到的输出是 0、45、56。问题是什么？

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

void add(int b);
void display();

struct node

{
int data;
struct node *next;
}*head, *ptr;

int main()
{
int a,b;
int i = 0;
head = malloc(sizeof(struct node));

printf("enter the number of entries:\n");
scanf("%d",&a);

while(i<a)
{
printf("enter the value:\n");
scanf("%d", &b);
add(b);
display();
i++;
}

return 0;

}

void display()
{
struct node *list = head;

while(list->next != 0)
{
printf("%d -> ",list->data);
list = list->next;
}

}

void add(int b)
{
struct node *p = head;
struct node *ptr = (struct node*)malloc(sizeof(struct node));
ptr->data = b;
ptr->next = 0;

while(p->next!=0)
{
p = p->next;
}

p->next = ptr;
}

Answer 1

在主目录

head = malloc(sizeof(struct node));
head->next = NULL;//necessary to set to NULL

显示时

printf("%d -> ", list->next->data);//The top node is not used