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iterator_count

(PHP 5 >= 5.1.0, PHP 7, PHP 8)

iterator_count计算迭代器中元素的个数

说明

iterator_count(Traversable|array $iterator): int

对迭代器中的元素计数。iterator_count() 不能保留 iterator 的当前位置。

参数

iterator

要计数的迭代器。

返回值

iterator 中的元素个数。

更新日志

版本 说明
8.2.0 iterator 的类型从 Traversable 扩展为 Traversable|array

示例

示例 #1 iterator_count() 示例

<?php
$iterator
= new ArrayIterator(array('recipe'=>'pancakes', 'egg', 'milk', 'flour'));
var_dump(iterator_count($iterator));
?>

以上示例会输出:

int(4)

示例 #2 iterator_count() 修改位置

<?php
$iterator
= new ArrayIterator(['one', 'two', 'three']);
var_dump($iterator->current());
var_dump(iterator_count($iterator));
var_dump($iterator->current());
?>

以上示例会输出:

string(3) "one"
int(3)
NULL

示例 #3 iterator_count()foreach 中循环

<?php
$iterator
= new ArrayIterator(['one', 'two', 'three']);
foreach (
$iterator as $key => $value) {
echo
"$key: $value (", iterator_count($iterator), ")\n";
}
?>

以上示例会输出:

0: one (3)

add a note

User Contributed Notes 2 notes

up
3
oleksii dot bulba at gmail dot com
2 years ago
Be aware that counting over NoRewindIterator will make items unavailable:

<?php

$iterator
= new ArrayIterator(['recipe'=>'pancakes', 'egg', 'milk', 'flour']);
$iterator = new NoRewindIterator($iterator);

var_dump($iterator->current());
var_dump(iterator_count($iterator));
var_dump($iterator->current());
$iterator->rewind(); // Does not work because it's NoRewindIterator
var_dump($iterator->current());
var_dump(iterator_count($iterator));

?>

Output:

<?php

/*
string(8) "pancakes"
int(4)
NULL
NULL
*/
int(0)

?>
up
2
info at ensostudio dot ru
3 years ago
Safe using:
<?php
$cnt
= iterator_count(clone $iterator);
?>
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