# SplObjectStorage::key

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

SplObjectStorage::key — Returns the index at which the iterator currently is

### 说明

public SplObjectStorage::key(): int

Returns the index at which the iterator currently is.

### 参数

此函数没有参数。

### 返回值

The index corresponding to the position of the iterator.

### 示例

示例 #1 SplObjectStorage::key() example

`<?php
$s = new SplObjectStorage();
$o1 = new stdClass;
$o2 = new stdClass;
$s->attach($o1, "d1");
$s->attach($o2, "d2");
$s->rewind();
while($s->valid()) {
$index = $s->key();
$object = $s->current(); // similar to current($s)
var_dump($index);
var_dump($object);
$s->next();
}
?>`

以上示例的输出类似于：

    int(0)
    object(stdClass)#2 (0) {
    }
    int(1)
    object(stdClass)#3 (0) {
    }

### 参见

- SplObjectStorage::rewind() - Rewind the iterator to the first storage element
- SplObjectStorage::current() - Returns the current storage entry
- SplObjectStorage::next() - Move to the next entry
- SplObjectStorage::valid() - Returns if the current iterator entry is valid

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