
SplQueue inherits from SplDoublyLinkedList. So, objects of SplQueue support methods push() and pop(). But please be advised that if you use push() and pop() methods on a SplQueue object, it behaves like a stack rather than a queue.

For example:

$q = new SplQueue();
$q->push(1);
$q->push(2);
$q->push(3);
$q->pop();
print_r($q);

Above code returns:

SplQueue Object
(
    [flags:SplDoublyLinkedList:private] => 4
    [dllist:SplDoublyLinkedList:private] => Array
        (
            [0] => 1
            [1] => 2
        )
)

Note that 3 got popped and *not* 1.

So, please make sure that you use only enqueue() and dequeue() methods on a SplQueue object and *not* push() and pop().

down

mostefa dot medjahed dot pro at gmail dot com ¶

1 year ago


As was said before, the push () and pop () methods on a SplQueue object, its behave like a stack rather than a queue.

Knowing that the enqueue () and dequeue () methods are respectively aliases of push () and shift () methods, we can also use SplQueue :: push () and SplQueue :: shift () for the same purpose as SplQueue :: enqueue and SplQueue :: dequeue.

down

MrStonedOne ¶

7 years ago


You can use shift/unshift and push/pop to dequeue/undequeue and queue/unqueue respectively. Really handy for those applications that use sockets where you might not know you can't send data until you attempt to.


for example, this is a function for an application that will un-dequeue the remainder of the data if socket_write indicated it did not write the entire contents of the provided data.


<?php

function processSendQueue($socket, $sendQueue) {

    while (!$sendQueue->isEmpty()) {

                            //shift() is the same as dequeue()

        $senditem = $sendQueue->shift();


        //returns the number of bytes written.

        $rtn = socket_write($socket, $senditem);

        if ($rtn === false) {

            $sendQueue->unshift($senditem);

            throw new exception("send error: " . socket_last_error($socket));

            return;

        }

        if ($rtn < strlen($senditem) {

            $sendQueue->unshift(substr($senditem, $rtn);

            break;

        }

    }

}

?>

down

lincoln dot du dot j at gmail dot com ¶

4 years ago


<?php
  
$queue = new SplQueue();
$queue->enqueue('A');
$queue->enqueue('B');
$queue->enqueue('C');

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

print_r($queue);
$queue->dequeue(); //remove first one
print_r($queue);

?>
Output

A
B
C
SplQueue Object
(
    [flags:SplDoublyLinkedList:private] => 4
    [dllist:SplDoublyLinkedList:private] => Array
        (
            [0] => A
            [1] => B
            [2] => C
        )

)
SplQueue Object
(
    [flags:SplDoublyLinkedList:private] => 4
    [dllist:SplDoublyLinkedList:private] => Array
        (
            [0] => B
            [1] => C
        )

)

down

Stingus ¶

5 years ago


Take care that SplQueue::valid() is not returning true if the queue has nodes. Use isEmpty() instead:

$queue = new SplQueue();
$queue->enqueue('A');
$queue->enqueue('B');
$queue->enqueue('C');
var_dump($queue->valid()); // false
var_dump(!$queue->isEmpty()); // true

down

booleantype at ya dot ru ¶

1 year ago


Answer to Manu Manjunath post (#114336).

IMO, pop() works as expected.

There are 2 main groups of methods:

1) pop() & push() are inherited from SplDoublyLinkedList and can be applied to SplStack as well as SplQueue (ie are "faceless"). It isn't about stack or queue; it's just about deleting / adding element to the end of the list;

2) the same situation with shift() & unshift(): it is just about adding an element to the beginning of the list, and doesn't matter, if we use it on SplStack or SplQueue.

So, yes, $q->pop(); will remove *last* element from SplQueue $q.

But enqueue() & dequeue() *are about* SplQueue. FIFO principle is realized by these methods, which were implemented *exactly* for queue purpose:
- enqueue() adds an element to the end of the queue and is alias for "faceless" push() (FI...);
- dequeue() removes element from the beginning of the queue and is alias for "faceless" shift() (...FO).

If you want to delete *next in line* element from *queue*, use dequeue().
If you want to delete *last* element from the list (doesn't matter, if it's queue or stack), use pop().

add a note

官方地址：https://www.php.net/manual/en/class.splqueue.php

有任何技术问题请点击这里网站运营推广招聘

IT PHP 编程语言 Linux 开发编程科技 Elasticsearch HTML/CSS/XML 网络 JAVA NoSQL 数据库面试 C/C++ Golang Git 算法操作系统正则表达式 Redis 互联网 MySql JavaScript 运维软件国际架构设计 Mac OS TCP/IP Excel Vim Windows Socket Oracle VR MongoDB Python 运营 MemCache 商业硬件电子娱乐设计 nginx 摄影游戏 WordPress HTTP 团建数码电器

php7 安装fileinfo扩展 preg_split — 通过一个正则表达式分隔字符串 php位值,解决 PHP 中 usort 在值相同时改变原始位置的问题 [PHP] inet_pton/inet_ntop IP地址转换函数 array_multisort() 多字段排序 PHPMailer设置utf8 PHPMailer字符集CharSet ADORecordSet对象 adodb手册 PHP 8.1 [鸟哥]PHP_INT_MIN 和 -9223372036854775808 opcache预加载 Composer的Packagist资源 mysql面试题 [鸟哥]PHP FFI详解 - 一种全新的PHP扩展方式 PHP7添加redis扩展 PHP mkdir()写出来的权限与mode值不符合 Packagist / Composer 中国全量镜像 PHP获取指定函数定义在哪个文件中及行号 adodb连接mysql多个数据库的问题 php设置cookie为httponly防止xss攻击

略微加速

PHP官方手册 - 互联网笔记

SplQueue 类

简介

类摘要

目录

User Contributed Notes 6 notes