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SplStack 类

(PHP 5 >= 5.3.0, PHP 7, PHP 8)

简介

SplStack 类的主要功能是通过将迭代模式设置为 SplDoublyLinkedList::IT_MODE_LIFO 来提供使用双向链表实现的栈。

类摘要

class SplStack extends SplDoublyLinkedList {

/* 继承的常量 */

public const int SplDoublyLinkedList::IT_MODE_LIFO;

public const int SplDoublyLinkedList::IT_MODE_FIFO;

public const int SplDoublyLinkedList::IT_MODE_DELETE;

public const int SplDoublyLinkedList::IT_MODE_KEEP;

/* 继承的方法 */

public SplDoublyLinkedList::add(int $index, mixed $value): void

public SplDoublyLinkedList::bottom(): mixed

public SplDoublyLinkedList::count(): int

public SplDoublyLinkedList::current(): mixed

public SplDoublyLinkedList::getIteratorMode(): int

public SplDoublyLinkedList::isEmpty(): bool

public SplDoublyLinkedList::key(): int

public SplDoublyLinkedList::next(): void

public SplDoublyLinkedList::offsetExists(int $index): bool

public SplDoublyLinkedList::offsetGet(int $index): mixed

public SplDoublyLinkedList::offsetSet(?int $index, mixed $value): void

public SplDoublyLinkedList::offsetUnset(int $index): void

public SplDoublyLinkedList::pop(): mixed

public SplDoublyLinkedList::prev(): void

public SplDoublyLinkedList::push(mixed $value): void

public SplDoublyLinkedList::rewind(): void

public SplDoublyLinkedList::serialize(): string

public SplDoublyLinkedList::setIteratorMode(int $mode): int

public SplDoublyLinkedList::shift(): mixed

public SplDoublyLinkedList::top(): mixed

public SplDoublyLinkedList::unserialize(string $data): void

public SplDoublyLinkedList::unshift(mixed $value): void

public SplDoublyLinkedList::valid(): bool

}

示例

示例 #1 SplStack 示例

<?php
$q = new SplStack();
$q[] = 1;
$q[] = 2;
$q[] = 3;
foreach ($q as $elem)  {
 echo $elem."\n";
}
?>

以上示例会输出：

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User Contributed Notes 3 notes

down

lsroudi at gmail dot com ¶

9 years ago

the SplStack is simply a SplDoublyLinkedList with an iteration mode IT_MODE_LIFO and IT_MODE_KEEP

down

lincoln dot du dot j at gmail dot com ¶

6 years ago

<?php
//SplStack Mode is LIFO (Last In First Out)
  
$q = new SplStack();

$q[] = 1;
$q[] = 2;
$q[] = 3;
$q->push(4);
$q->add(4,5);

$q->rewind();
while($q->valid()){
    echo $q->current(),"\n";
    $q->next();
}
?>

Output
5
4
3
2
1

down

-9

daryledesilva at gmail dot com ¶

4 years ago

<?php

// Exercise: Implement Queue using Stacks

class MyQueue {
    protected $queue;
    
    /**
     * Initialize your data structure here.
     */
    function __construct() {
        $this->queue = new \SplStack;
    }
  
    /**
     * Push element x to the back of queue.
     * @param Integer $x
     * @return NULL
     */
    function push($x) {
        $this->queue->push($x);
    }
  
    /**
     * Removes the element from in front of queue and returns that element.
     * @return Integer
     */
    function pop() {
        $length = count($this->queue);
        $temp = [];
        while(!$this->queue->isEmpty()){
            $rv = $this->queue->pop();
            if(!$this->queue->isEmpty()){
                $temp[] = $rv;
            }
        }
        for($i = count($temp)-1; $i >= 0; $i--){
            $this->queue->push($temp[$i]);   
        }
        return $rv;
    }
  
    /**
     * Get the front element.
     * @return Integer
     */
    function peek() {
        return $this->queue->bottom();
    }
  
    /**
     * Returns whether the queue is empty.
     * @return Boolean
     */
    function empty() {
        return $this->queue->isEmpty();
    }
}

/**
 * Your MyQueue object will be instantiated and called as such:
 * $obj = MyQueue();
 * $obj->push($x);
 * $ret_2 = $obj->pop();
 * $ret_3 = $obj->peek();
 * $ret_4 = $obj->empty();
 */

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