Returns the index at which the iterator currently is

# 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 function 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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