链表给出了这个警告

Question

我是C的新手并试图从书中学习一些链表。我尝试编译此示例代码，但在下面获取这些警告。

警告

  

linkedlist.c：29：1：警告：隐式声明函数'display'[-Wimplicit-function-declaration]    显示器（安培;友好）;    ^   linkedlist.c：顶级：   linkedlist.c：31：14：错误：未知类型名称'island'

提前感谢。

#include<stdio.h>
#include<string.h>
int main(){

  typedef struct island{
    char *name;
    char *opens;
    char *close;
    struct island *next;
  }island;

  island amity  = { "Amity" , "09:00", "17:00", NULL};
  island craggy  = { "Craggy" , "09:00", "17:00", NULL};
  island isla_nublar = { "isla Nublar" , "09:00", "17:00", NULL};
  island sutter  = { "Shutter" , "09:00", "17:00", NULL};


  amity.next = &craggy;
  craggy.next = &isla_nablar;
  isla_nabla.next = &shutter;


  island skull  = { "Skull" , "09:00", "17:00", NULL};
  isla_nabla.next = &skull;
  skull.next = &shutter;
  display(&amity);
}
void display(island *start){
  island *i = start;
  for(; i != NULL; i = i->next){
    printf("NAme: %s open : %s-%s\n", i->name,i->opens,i->close);
  }
}