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

interface Iterator extends Traversable {
/* 方法 */
public current(): mixed
public key(): mixed
public next(): void
public rewind(): void
public valid(): 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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