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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。

    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：

    3
2
1

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    User Contributed Notes 3 notes

    up
    37
    lsroudi at gmail dot com
    10 years ago
    the SplStack is  simply a SplDoublyLinkedList with  an iteration mode IT_MODE_LIFO and IT_MODE_KEEP
    up
    7
    lincoln dot du dot j at gmail dot com
    7 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
    up
    -6
    daryledesilva at gmail dot com
    5 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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