PHP double linked list (SplDoublyLinkedList) introduction and usage examples, php linked list_PHP tutorial

Introduction and usage examples of PHP Doubly Linked List (SplDoublyLinkedList), PHP linked list

Double linked list is an important linear storage structure. For each node in the doubly linked list, not only To store its own information, it also needs to save the addresses of predecessor and successor nodes.

The SplDoublyLinkedList class in PHP SPL provides operations on doubly linked lists.
The SplDoublyLinkedList class summary is as follows:

SplDoublyLinkedList implements Iterator  , ArrayAccess  , Countable  {
 
  public __construct ( void )
  public void add ( mixed $index , mixed $newval )
  //双链表的头部节点
  public mixed top ( void )
  //双链表的尾部节点
  public mixed bottom ( void )
  //双联表元素的个数
  public int count ( void )
  //检测双链表是否为空
  public bool isEmpty ( void )
 
 
  //当前节点索引
  public mixed key ( void )
  //移到上条记录
  public void prev ( void )
  //移到下条记录
  public void next ( void )
  //当前记录
  public mixed current ( void )
  //将指针指向迭代开始处
  public void rewind ( void )
  //检查双链表是否还有节点
  public bool valid ( void )
 
  //指定index处节点是否存在
  public bool offsetExists ( mixed $index )
  //获取指定index处节点值
  public mixed offsetGet ( mixed $index )
  //设置指定index处值
  public void offsetSet ( mixed $index , mixed $newval )
  //删除指定index处节点
  public void offsetUnset ( mixed $index )
 
  //从双链表的尾部弹出元素
  public mixed pop ( void )
  //添加元素到双链表的尾部
  public void push ( mixed $value )
 
  //序列化存储
  public string serialize ( void )
  //反序列化
  public void unserialize ( string $serialized )
 
  //设置迭代模式
  public void setIteratorMode ( int $mode )
  //获取迭代模式SplDoublyLinkedList::IT_MODE_LIFO (Stack style) SplDoublyLinkedList::IT_MODE_FIFO (Queue style)
  public int getIteratorMode ( void )
 
  //双链表的头部移除元素
  public mixed shift ( void )
  //双链表的头部添加元素
  public void unshift ( mixed $value )
 
}

It’s also easy to use

$list = new SplDoublyLinkedList();
$list->push('a');
$list->push('b');
$list->push('c');
 
$list->unshift('top');
$list->shift();
 
print_r(array(
  'pop' => $list->pop(),
  'count' => $list->count(),
  'isEmpty' => $list->isEmpty(),
  'bottom' => $list->bottom(),
  'top' => $list->top()
));
 
$list->setIteratorMode(SplDoublyLinkedList::IT_MODE_FIFO);
print_r($list->getIteratorMode());
 
for($list->rewind(); $list->valid(); $list->next()) {
  echo $list->current().PHP_EOL;
}
 
print_r($a = $list->serialize());
//print_r($list->unserialize($a));
 
$list->offsetSet(0,'new one');
$list->offsetUnset(0);
print_r(array(
  'offsetExists' => $list->offsetExists(4),
  'offsetGet' => $list->offsetGet(0),
 
));
print_r($list);

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