Iterator（迭代器）接口

    (PHP 5, PHP 7, PHP 8)

    简介

    可在内部迭代自己的外部迭代器或类的接口。

    接口摘要

    interfaceIteratorextendsTraversable {
    publiccurrent(): mixed
    publickey(): mixed
    publicnext(): void
    publicrewind(): void
    publicvalid(): bool
    }

    预定义迭代器

    PHP 已经提供了一些用于日常任务的迭代器。 详细列表参见 SPL 迭代器。

    示例

    示例 #1 基本用法

    这个例子展示了使用 foreach 时，迭代器方法的调用顺序。

    <?php
    class myIterator implements Iterator {
    private     $position = 0;
    private     $array = array(
    "firstelement",
    "secondelement",
    "lastelement",
    );

    public function     __construct() {
    $this->position = 0;
    }

    public function     rewind(): void {
    var_dump(__METHOD__);
    $this->position = 0;
    }

    #[    \ReturnTypeWillChange]
    public function     current() {
    var_dump(__METHOD__);
    return     $this->array[$this->position];
    }

    #[    \ReturnTypeWillChange]
    public function     key() {
    var_dump(__METHOD__);
    return     $this->position;
    }

    public function     next(): void {
    var_dump(__METHOD__);
    ++    $this->position;
    }

    public function     valid(): bool {
    var_dump(__METHOD__);
    return isset(    $this->array[$this->position]);
    }
    }

    $it = new myIterator;

    foreach(    $it as $key => $value) {
    var_dump($key, $value);
    echo     "\n";
    }
    ?>

    以上示例的输出类似于：

     string(18) "myIterator::rewind" string(17) "myIterator::valid" string(19) "myIterator::current" string(15) "myIterator::key" int(0) string(12) "firstelement" string(16) "myIterator::next" string(17) "myIterator::valid" string(19) "myIterator::current" string(15) "myIterator::key" int(1) string(13) "secondelement" string(16) "myIterator::next" string(17) "myIterator::valid" string(19) "myIterator::current" string(15) "myIterator::key" int(2) string(11) "lastelement" string(16) "myIterator::next" string(17) "myIterator::valid"

    参见

    参见 遍历对象。

    目录

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